Journal of Affective Disorders 175 (2015) 209–216
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Research report
The course of depressive symptoms as measured by the Cornell scale for depression in dementia over 74 months in 1158 nursing home residents Tom Borza a,b,n, Knut Engedal c, Sverre Bergh a, Maria Lage Barca c, Jūratė Šaltytė Benth a,d,e, Geir Selbæk a,c,d a
Centre for Old Age Psychiatric Research, Innlandet Hospital Trust, Ottestad, Norway Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway Norwegian National Advisory Unit on Aging and Health, Vestfold Health Trust, Tønsberg, Norway d Institute of Clinical Medicine, Campus AHUS, University of Oslo, Norway e HØKH, Research Centre, Akershus University Hospital, Norway b c
art ic l e i nf o
a b s t r a c t
Article history: Received 29 August 2014 Received in revised form 21 December 2014 Accepted 24 December 2014 Available online 31 December 2014
Background: Depressive symptoms and depression are common in nursing home residents. However, longitudinal studies of depression in nursing home residents are scarce and the sample sizes are small. This study aimed to investigate the course of depressive symptoms as measured by the Cornell Scale for Depression in Dementia (CSDD) and associated explanatory demographic and clinical variables. Methods: A longitudinal study over 74 months of 1158 nursing home residents aged 50 years and older from twenty six nursing homes in Norway where data was collected at five time points. Results: “Irritability” was the most prevalent, incident and persistent CSDD symptom. Compared with the baseline assessment, the likelihood of the mood symptoms “suicidal ideation,” “pessimism” and “delusions” being present was lower at all subsequent assessments. This persisted after adjusting for the severity of dementia. The severity of depression as measured by CSDD decreased over 74 months when adjusting for relevant resident variables. Poorer physical health, higher number of medications, more severe dementia and use of antidepressants were associated with higher depression score. Limitations: Depression and dementia were not diagnosed according to standardized diagnostic criteria. The use of CSDD did not include a clinician's interview with the patient. This could have implications for the generalization of the results. Conclusion: This study adds important knowledge about the long-term course of depressive symptoms and depression for residents in nursing homes, and underlines the importance to pay close attention to the overlap between depression and dementia symptoms when evaluating depression in this setting. & 2014 Elsevier B.V. All rights reserved.
Keywords: Depression Nursing home Longitudinal study Dementia
1. Introduction Depression is common in nursing home residents (Jongenelis et al., 2004). Median prevalence of major depressive disorder is 10% and median prevalence of depressive symptoms is 29% among older adults in long-term care, according to a recent systematic review (Seitz et al., 2010). Incidence rates of depression among institutionalized patients followed for 6–14 months vary between 1.8% and 14.9% (Barca et al., 2010; Boorsma et al., 2012; Katz et al., 1989; Parmelee et al., 1992; Payne et al., 2002; Smalbrugge et al., 2006). Persistence rates of clinically significant depressive symptoms vary between 44.8% and 63.3% (Barca et al., 2010; Smalbrugge et al.,
n
Corresponding author. Tel.: þ 47 91799639; fax: þ 47 62581401. E-mail address: [email protected] (T. Borza).
http://dx.doi.org/10.1016/j.jad.2014.12.053 0165-0327/& 2014 Elsevier B.V. All rights reserved.
2006) and show that depressive symptoms may follow a chronic course. The prevalence of dementia among nursing home residents varies between 63.9% and 81.0% (Selbaek et al., 2007; Wancata et al., 2003). Depression and dementia commonly coexist (McSweeney and O'Connor, 2008) and depression may present differently in patients with dementia compared to patients without dementia. New diagnostic criteria for depression in dementia have been suggested (Olin et al., 2002b). The Cornell Scale for Depression in Dementia (CSDD) has been validated for patients with and without dementia and is widely used in clinical practice and research, making CSDD a useful tool for assessing depression among nursing home residents (Alexopoulos et al., 1988a, b; Snowdon, 2010). As previous research indicates that the symptom profile of depression in dementia may differ from depression without dementia (Li et al., 2001; Olin et al., 2002b), the course of individual
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depressive symptoms in nursing home residents is of particular interest. Longitudinal studies of depression in nursing home residents are scarce and the sample sizes are small. Some of these longitudinal studies have shown that variables such as poor physical health (Rozzini et al., 1996), cognitive impairment (McSweeney and O'Connor, 2008), functional disability (Parmelee et al., 1992), a higher depression score at baseline, a shorter stay in the nursing home (Barca et al., 2010) and more years of education (Smalbrugge et al., 2006) are associated with more severe depression. One study in a highly specialized long-term care facility found a decline in depression during the first year after admission (Payne et al., 2002). However, results from longitudinal studies are conflicting regarding whether and how the variables described above are related to depression (Barca et al., 2010; Boorsma et al., 2012; McSweeney and O'Connor, 2008; Parmelee et al., 1992; Payne et al., 2002; Rozzini et al., 1996; Smalbrugge et al., 2006). We could not find any longitudinal study on depression in nursing home residents with a follow-up period of more than 14 months and no longitudinal study have investigated the course of the individual symptoms of depression. Here, we report the results of a longitudinal study including 1158 nursing home residents aged Z 50 years. The study assessed the course of individual depressive symptoms at five time points during 74 months follow-up and investigated whether the level of dementia influenced the prevalence and course of CSDD symptoms. Furthermore, we investigated which other demographic and clinical variables correlated with depression as measured by the CSDD.
2. Methods This study is a Norwegian longitudinal nursing home study. Baseline data describing the frequency of depressive symptoms and its correlates (Barca et al., 2008, 2009), as well as 12-month follow-up data examining the prevalence, incidence and persistence rates of clinically significant depressive symptoms have been published previously (Barca et al., 2010). 2.1. Participants All eligible residents in 26 nursing homes in four Norwegian counties were asked to participate. Nursing homes were selected in order to reflect the distribution of the entire nursing home population in the four counties (Selbaek et al., 2008). A minimum stay of 14 days was required for inclusion in the study. A total of 1165 patients were eligible, of which two were not willing to participate and five were excluded due to age o50 years, leaving 1158 patients in the study. The mean length of nursing home stay at the baseline assessment (T0) was 941 (SD ¼1014) days. The residents were then assessed after 12 (T1), 31 (T2), 53 (T3) and 74 months (T4) (see Fig. 1 for attrition from T0 to T4). The mean follow-up times were: 354 days (SD ¼ 15) from T0 to T1; 934 days (SD ¼34) from T0 to T2; 1580 days (SD ¼ 42) from T0 to T3; and 2232 (SD ¼79) days from T0 to T4. 2.2. Data collection Sixteen research nurses used a standardized interview and collected data from November 2004 to September 2011. Data was collected from the residents' records and interviews with residents' primary carers, who were all registered nurses. All research nurses attended a training program on how to conduct the interview, prior to all assessments. The CSDD was used to rate depressive symptoms in detail. The CSDD consists of 19 items which are rated 0 (no symptoms), 1 (mild symptoms) or 2 (severe
symptoms) and also allows a rating “item unable to evaluate”. For analyses on the course of the depressive symptoms, the 19 CSDD items were dichotomised to present (1 or 2) or absent (0). Previous research has shown that the items of the CSDD can be divided into a mood factor (anxiety, sadness, suicidal ideation, poor selfesteem, pessimism and delusion) and a non-mood factor (lack of joy, irritability, agitation, retardation, loss of interest, appetite loss, weight loss, lack of energy, diurnal variation, difficulty falling asleep, multiple awakening and early morning awakening) (Barca et al., 2008). Before calculating the sum scores of the CSDD (total, mood and non-mood CSDD scores), the rating “item unable to evaluate” was replaced by a score of 0. This method of imputation is in line with what has been recommended in previous research (Leontjevas et al., 2012). However, the CSDD scores were only calculated where at most 20% of the CSDD items had the rating “item unable to evaluate.” We used the Clinical Dementia Rating scale (CDR) to assess the severity of dementia (Hughes et al., 1982). The global score of this six-item instrument is generated using an algorithm giving precedence to memory, and the scoring ranges from 0 (no dementia) to 3 (severe dementia). In the analysis we also present the CDR sum of boxes score (which carries a maximum score of 18, where a higher score denotes more severe dementia) which has been shown to be highly correlated with the global CDR score (O'Bryant et al., 2008). In the baseline sample (n ¼1158) the (Spearman's) correlation coefficient between the CDR global score and CDR sum of boxes score was 0.93. The Physical Self-Maintenance Scale (PSMS) (Lawton and Brody, 1969) was used to assess the residents' ability to perform the personal activities of daily living. PSMS consists of six items and a higher score denotes greater impairment (maximum possible score of 30). Physical health was rated with the General Medical Health Rating scale (GMHR), a four-point (good, fair, poor, very poor) global rating scale for medical comorbidity. The GMHR takes into account each patient's number of general medical conditions, the severity of those conditions and the use of medications (Lyketsos et al., 1999). Demographic data, the residents' diagnoses and regular medication were collected from medical records. We classified the medication according to the Anatomical Therapeutic Chemical classification system (ATC) (WHO, 2014). To analyse the dose of antidepressants we used Defined Daily Dose (DDD), a World Health Organization statistical measure of drug consumption that gives the assumed average maintenance dose per day for a drug used for its main indication in adults (WHO, 2014). 2.3. Statistical analysis The following definitions were used in all analyses: prevalence (point prevalence) is the proportion of residents with the symptom present at an individual assessment; cumulative prevalence is the proportion of residents with the symptom present at at least one of the five assessments; incidence rate is the ratio of residents who presented the symptom at one assessment to those who were symptom free at the preceding assessment; persistence rate is the ratio of residents who presented the symptom at one assessment to those who presented the symptom at the preceding assessment. Data was analysed using the Statistical Program for Social Science package (SPSS v. 22.0) and Statistical Analysis System (SAS v. 9.3). Differences in clinical and demographic characteristics between completers and non-completers were analysed by independent sample t-test. Days of stay was symmetrised by a logarithmic transformation before applying t-test. For categorical data the χ2-test was employed. Time trend in the 19 depressive symptoms dichotomized to present or absent was assessed by a logistic regression model for repeated observations. As the observations also exhibited a hierarchical structure with residents nested within a ward and the
T. Borza et al. / Journal of Affective Disorders 175 (2015) 209–216
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Fig. 1. Flow chart describing attrition from T0 to T4.
wards nested within a nursing home, a three-level logistic regression model with random intercepts was estimated (SAS GLIMMIX procedure). Such a model adjusts estimated odds ratios (OR) for intra-resident correlations appearing due to repeated measurements within different levels of hierarchy. Both linear and secondorder time components were included as fixed effects. A secondorder component was only left in the model if significant. Baseline was chosen as the reference time point so that OR represents the change in time with respect to baseline. Crude ORs were further adjusted for the CDR sum of boxes score observed simultaneously with depressive symptoms. Interaction between time and CDR sum of boxes score was also assessed, but was not significantly different from 0 in all models and therefore excluded. A three-level linear mixed model (SAS MIXED procedure) with random intercepts for residents nested within wards and wards nested within nursing homes was fitted for assessing the time trend in depression scores (total CSDD, mood CSDD and non-mood CSDD). Dummies for each time point were included in the model as fixed effects with baseline as reference, capturing a non-linear nature of time trend in depression scores. Regression coefficients are to be interpreted as average change in CSDD score from baseline to a certain time point. Time trend estimates were further adjusted for age, days of stay, gender, education, marital status, physical health, CDR sum of boxes score, PSMS score, use of antidepressants and number of medications. In addition, a three-level growth model with random intercepts for residents nested within wards and wards nested within nursing homes was also estimated to assess time change in CDR sum of boxes score. We considered a p-value o0.05 as statistically significant.
2.4. Ethical and legal considerations Information about the study was given to the residents and their family members. Explicit consent was not required for enrolment, but the residents or their next of kin were informed
that they could refuse to participate at any stage of the study. The Regional Ethics Committee, the Data Inspectorate and the Directorate for Health and Social Affairs approved this procedure.
3. Results The clinical and demographic characteristics of the sample at different time points (T0–T4) are shown in Table 1. The DDD of antidepressants varied between 0.8 (SD ¼ 0.5) and 1.0 (SD ¼0.5). Of the 1158 patients, 98 (8.5%) completed T4 (completers). The completers were younger, had less severe dementia, better physical health and performed better in activities of daily living at T0 than the non-completers. At T0, 80.5% of the total sample had dementia, defined by a score Z1 on the CDR scale, 33.7% had severe dementia (CDR score¼3). The severity of dementia increased during follow-up, as the CDR-sum of boxes score increased non-linearly in time (both first- and second-order time components were significant [p o0.001]). The prevalence, incidence and persistence rates of individual CSDD symptoms are presented in Table 2. “Irritability,” “multiple physical complaints,” “anxiety,” and “sadness” had a cumulative prevalence of more than 70%, whereas “early morning awakening” and “weight loss” had a cumulative prevalence of less than 30%. The incidence rates of “irritability”, “multiple physical complaints”, “anxiety” and “sadness” were higher than 20% at at least three of the four time intervals. The incidence rates of “suicidal ideation”, “early morning awakening”, “delusions”, and “poor self-esteem” were lower than 10% at at least three of the four time intervals. “Irritability”, “anxiety” and “sadness” had persistence rates of Z 50% at all time intervals. The persistence rates of “early morning awakening” were lower than 25% at all time intervals. Table 3 presents the changes in OR of the individual CSDD symptoms being present during follow-up. Compared to T0 the odds of symptoms being present at later time points increased for: “lack of joy” at T3 and T4; “irritability” at T1–3; “agitation” at T1 and
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Table 1 Demographic and clinical characteristics of the study sample at T0–T4.
Age in years – mean (SD) Female gender (%) Education, o 9 years (%) Married (%) Days of stay – mean (SD) CSDD – mean (SD) CDR Z 1 (%)n CDR, sum of boxes score – mean (SD) Physical health (GMHR poor or very poor) (%) Number of drugs – mean (SD) Use of psychotropic drugs (%) Use of antidepressants (%) Defined daily dose of antidepressants – mean (SD) PSMS sum – mean (SD)
T0 (n ¼1158)
T1 (n¼ 786)
T2 (n¼ 394)
T3 (n¼ 209)
T4 (n¼ 98)
84.5 (7.3) 72.7 74.7 18.9 941 (1014) 5.4 (5.2) 80.5 11.3 (5.3) 48.5 6.0 (3.0) 72.9 38.1 1.0 (0.5) 18.1 (5.4)
85.0 (7.4) 74.8 74.3 17.9 1306 (1044) 4.7 (4.5) 83.8 11.9 (5.3) 46.8 6.8 (3.2) 71.5 37.3 1.0 (0.5) 18.8 (5.3)
86.4 (7.4) 75.4 75.7 15.5 1890 (1165) 5.4 (4.5) 83.6 12.3 (5.3) 46.4 6.4 (3.4) 70.6 36.5 1.0 (0.5) 19.8 (5.2)
87.6 (7.5) 76.6 75.5 13.5 2519 (1175) 5.2 (4.5) 90.7 13.5 (4.7) 51.0 6.5 (3.3) 69.4 35.4 0.8 (0.5) 20.8 (5.0)
88.0 (7.8) 71.4 77.9 9.3 3006 (1470) 4.5 (3.9) 81.3 13.3 (5.1) 51.6 6.6 (3.2) 63.3 32.7 0.9 (0.5) 21.2 (5.1)
CSDD¼ Cornell scale for depression in dementia, CDR¼ clinical dementia rating, GMHR¼ the general medical health rating scale, PSMS ¼ physical self-maintenance scale, SD ¼ standard deviation. n CDRZ 1¼ residents with dementia according to CDR.
Table 2 Prevalence, incidence and persistence rates of depressive symptoms according to the Cornell Scale for Depression in Dementia (CSDD) at the different time points and intervals. Prevalence (%)
n¼ Item: Anxiety Sadness Lack of joy Irritability Agitation Retardation Multiple physical complaints Loss of interest Appetite loss Weight loss Lack of energy Diurnal variation Difficulty falling asleep Multiple awakening Early morning awakening Suicidal ideation Poor self-esteem Pessimism Delusions
Incidence (%)
Persistence (%)
T0 1158
T1 786
T2 394
T3 209
T4 98
Cum.n 98
T0–T1 786
T1–T2 394
T2–T3 209
T3–T4 98
T0–T1 786
T1–T2 394
T2–T3 209
T3–T4 98
40 34 19 41 17 24 35 19 12 8 22 17 10 24 9 10 17 28 14
39 33 17 44 17 23 34 11 15 10 15 16 12 21 7 7 13 20 10
44 34 19 47 25 27 38 13 17 9 19 18 11 25 8 8 20 20 13
35 40 30 49 17 28 52 11 20 11 16 18 12 19 6 6 12 14 11
28 28 29 43 19 18 29 12 17 14 18 24 10 19 5 4 8 11 4
72 71 55 83 58 51 78 43 42 28 53 57 39 63 26 31 48 53 37
27 23 13 27 12 16 26 9 14 9 13 11 10 17 6 5 8 11 8
31 23 15 31 21 18 25 13 17 9 18 16 10 21 7 6 13 13 11
24 30 24 32 9 17 42 7 20 11 13 17 11 12 6 4 7 10 6
16 12 24 30 16 11 20 14 12 12 20 18 8 14 6 3 6 11 3
59 56 36 68 41 50 50 20 26 32 25 38 32 34 17 31 41 47 25
63 61 43 68 50 57 65 21 21 18 18 34 16 44 24 56 60 50 30
54 58 62 69 38 65 72 43 30 25 34 24 24 39 11 31 43 35 45
50 50 40 57 28 38 39 0 41 33 8 47 20 36 0 20 30 29 13
n
Cum. ¼ Cumulative prevalence.
T2; “multiple physical complaints” at T1–4; “appetite loss” at T1–4 and “weight loss” at T1–4. When adjusting for time-dependent CDR sum of boxes score, the significant increase did not persist for “irritability”, “agitation”, “weight loss” and “lack of joy” (at T3). Compared to T0 the odds of symptoms being present at later time points decreased for: “anxiety” at T4; “loss of interest” at T1–3; “lack of energy at T1-3; “suicidal ideation” at T1–4; “pessimism at T1–4; “delusions at T1–4. When adjusting for time-dependent CDR sum of boxes score, the significant decreases persisted. Fig. 2 demonstrates the course of the mean score of the total CSDD, the mean score of the mood and the non-mood factors of the CSDD for those completing the different time points. The changes in depression scores according to the CSDD from T0 to T4 in mixed model are presented in Table 4. In the unadjusted model there was a decrease compared to T0 in total CSDD score at T1, a decrease in mood CSDD score at T1 and T4 and a decrease in non-mood CSDD score at T1. In the adjusted model there was a
decrease compared to T0 in total CSDD score at T1 and T4, a decrease in mood CSDD score at T1, T3 and T4 and a decrease in non-mood CSDD score at T1. Poorer physical health, more severe dementia and a higher number of medications were associated with more severe depressive symptoms (CSDD total score, CSDD mood and CSDD nonmood score). The use of antidepressants was associated with higher total CSDD score and mood CSDD score. Length of stay was associated with a lower total CSDD score. Lower level of functioning was associated with a lower mood CSDD score. Lower age was associated with a higher non-mood CSDD score.
4. Discussion This longitudinal study of nursing home patients with five assessments over a 74-month follow-up showed that the severity
T. Borza et al. / Journal of Affective Disorders 175 (2015) 209–216
213
Table 3 Logistic regression model for hierarchical data showing crude odds ratio (OR) and OR adjusted for time-dependent clinical dementia rating (CDR) sum of boxes scores (adj) with corresponding 95% confidence interval for depressive symptoms according to the Cornell scale for depression in dementia (CSDD) at different time points: T0: n¼ 1158, T1: n¼786, T2: n¼ 393; T3: n¼ 209; and T4: n ¼98. Time point T0 is reference. Item
T1
T2
T3
T4
T1 (adj)
T2 (adj)
T3 (adj)
T4 (adj)
Anxiety1 Sadness Lack of joy1 Irritability1 Agitation1 Retardation Multiple physical complaints Loss of interest1 Appetite lost Weight loss Lack of energy1 Diurnal variation Difficulty falling asleep Multiple awakening Early morning awakening Suicidal ideation Poor selfesteem Pessimism
1.08 (0.95; 1.22) 1.02 (0.96; 1.08) 0.97 (0.84; 1.13) 1.19 (1.05; 1.34)n 1.19 (1.02; 1.38)n 1.03 (0.97; 1.10) 1.09 (1.03; 1.15)nn
1.07 (0.85; 1.34) 1.05 (0.91; 1.21) 1.08 (0.83; 1.41) 1.39 (1.11; 1.73)nn 1.35 (1.03; 1.78)n 1.09 (0.92; 1.28) 1.25 (1.09; 1.44)nn
0.88 (0.68; 1.13) 1.08 (0.84; 1.39) 1.53 (1.14; 2.04)nn 1.40 (1.08; 1.81)n 1.27 (0.94; 1.72) 1.16 (0.87; 1.53) 1.47 (1.15; 1.87)nn
0.60 (0.39; 0.92)n 1.12 (0.79; 1.58) 2.66 (1.72; 4.11)nnn 1.19 (0.78; 1.82) 0.96 (0.59; 1.58) 1.22 (0.83; 1.81) 1.71 (1.22; 2.39)nn
1.06 (0.93; 1.20) 1.01 (0.95; 1.07) 0.90 (0.77; 1.05) 1.12 (0.99; 1.28) 1.12 (0.96; 1.31) 0.98 (0.91; 1.04) 1.08 (1.02; 1.15)nn
1.02 (0.81; 1.28) 1.02 (0.88; 1.18) 0.91 (0.69; 1.20) 1.23 (0.98; 1.55) 1.16 (0.88; 1.54) 0.94 (0.79; 1.11) 1.23 (1.06; 1.42)nn
0.82 (0.63; 1.07) 1.03 (0.80; 1.33) 1.20 (0.89; 1.62) 1.18 (0.91; 1.54) 0.97 (0.71; 1.34) 0.90 (0.67; 1.20) 1.42 (1.11; 1.82)nn
0.56 (0.36; 0.87)n 1.05 (0.73; 1.49) 2.04 (1.28; 3.25)nn 0.99 (0.63; 1.53) 0.66 (0.39; 1.13) 0.86 (0.57; 1.29) 1.64 (1.16; 2.31)nn
0.72 (0.60; 0.85)nnn 1.13 (1.06; 1.20)nnn 1.10 (1.02; 1.19)n 0.80 (0.69; 0.93)nn
0.54 (0.40; 0.74)nnn 1.37 (1.16; 1.62)nnn 1.29 (1.05; 1.58)n 0.67 (0.51; 0.87)nn
0.58 (0.41; 0.81)nn 0.89 (0.50; 1.57)
0.68 (0.57; 0.81)nnn 1.08 (1.01; 1.16)n
0.47 (0.35; 0.65)nnn 1.23 (1.04; 1.46)n
0.47 (0.34; 0.67)nnn 1.42 (1.06; 1.91)n
0.71 (0.41; 1.24)
1.54 (1.09; 2.18)n 0.70 (0.52; 0.94)n
1.83 (1.13; 2.97)n 0.96 (0.59; 1.54)
1.05 (0.98; 1.12)
1.13 (0.95; 1.34)
1.23 (0.92; 1.64)
1.03 (0.96; 1.12)
1.09 (0.89; 1.33)
0.95 (0.90; 1.02)
Delusions n
p o 0.05; 1
nn
1.71 (1.29; 2.28)nn 2.12 (1.42; 3.16)nn
1.64 (1.09; 2.46)n
1.31 (0.92; 1.86) 1.45 (0.89; 2.38) 0.59 (0.44; 0.80)nn 0.76 (0.47; 1.23)
1.33 (0.89; 1.99)
1.06 (0.98; 1.15) 1.17 (0.95; 1.86) 0.77 (0.66; 0.89)nn 0.60 (0.46; 0.79)nnn 1.03 (0.97; 1.10) 1.09 (0.92; 1.29)
1.15 (0.86; 1.55)
1.22 (0.81; 1.84)
1.16 (0.83; 1.64)
1.23 (0.77; 1.99)
1.01 (0.93; 1.09)
1.02 (0.83; 1.25)
1.04 (0.73; 1.47)
1.06 (0.65; 1.72)
0.89 (0.76; 1.04)
0.81 (0.62; 1.07)
0.75 (0.51; 1.10)
0.94 (0.88; 1.00)
0.85 (0.72; 1.00)
0.76 (0.57; 1.00)
0.68 (0.46; 1.00)
0.93 (0.85; 1.03)
0.84 (0.65; 1.08)
0.74 (0.48; 1.14)
0.65 (0.36; 1.19)
0.92 (0.84; 1.02)
0.81 (0.63; 1.05)
0.70 (0.45; 1.09)
0.61 (0.33; 1.13)
0.88 (0.78; 0.98)n
0.71 (0.53; 0.95)n
0.56 (0.34; 0.91)n
0.44 (0.22; 0.88)n
0.87 (0.78; 0.97)n
0.69 (0.52; 0.93)n
0.54 (0.32; 0.88)n
0.42 (0.21; 0.84)n
0.93 (0.86; 1.01)
0.83 (0.67; 1.02)
0.72 (0.50; 1.04)
0.63 (0.38; 1.06)
0.92 (0.85; 1.00)
0.81 (0.66; 1.01)
0.70 (0.49; 1.02)
0.61 (0.37; 1.03)
0.82 (0.76; 0.89)nnn 0.90 (0.82; 0.98)n
0.61 (0.49; 0.74)nnn 0.75 (0.59; 0.96)n
0.42 (0.30; 0.60)nnn 0.62 (0.41; 0.93)n
0.30 (0.19; 0.49)nnn
0.83 0.62 0.44 0.32 (0.20; 0.53)nnn (0.77; 0.90)nnn (0.51; 0.77)nnn (0.31; 0.63)nnn 0.88 (0.80; 0.97)nn 0.72 (0.56; 0.92)nn 0.57 (0.37; 0.86)nn 0.45 (0.25; 0.81)nn
p o 0.01;
0.51 (0.29; 0.90)n
nnn
p o 0.001.
Model contains a non-linear (second-order) trend component.
7
Total CSDD Non−mood CSDD Mood CSDD
Mean CSDD score
6 5 4 3 2 1 0 0(=T0)
12(=T1)
31(=T2)
53(=T3)
74(=T4)
Time in months Fig. 2. The course of the mean total, mood and non-mood of the Cornell scale for Depression in Dementia (CSDD) scores, (and 95% confidence intervals) for those completing T0 (n¼ 1158), T1 (n¼ 786), T2 (n¼ 394), T3 (n ¼209) and T4 (n ¼98).
of depression as measured by CSDD decreased over time after adjusting for relevant demographic and clinical variables in a mixed linear model. 4.1. Individual symptoms The course of individual symptoms varied. A previous publication has proposed that “irritability” should be used as a criterion of depression in subjects with dementia as it may be regarded to
contain elements of dysphoria (Olin et al., 2002a). In the present study 80.5% of the study population had dementia at baseline. “Irritability” was the most prevalent, incident and persistent item of the CSDD. This is in line with a study in geriatric psychiatry services (Verkaik et al., 2009) and another addressing residents in nursing homes (Ballard et al., 1996a), which both show that “irritability” is highly prevalent among dementia sufferers with comorbid depression. The study populations in these two studies were somewhat different from the present, and neither of the two
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Table 4 Mixed model for change (time trend) in depression score according to the Cornell Scale for Depression in Dementia (CSDD) from T0 to T4, and adjusted for control variables. Total CSDD
Mood CSDD
Non-mood CSDD
Unadjusted Intercept T0 T1 T2 T3 T4
5.31 ( o 0.001)1 0 0.52 (0.005)n 0.39 (0.109)n 0.55 (0.087)n 0.30 (0.512)n
1.77 ( o0.001)2 0 0.26 (0.002)nn 0.04 (0.728)nn 0.26 (0.073)nn 0.68 ( o0.001)nn
3.09 (o 0.001)3 0 0.26 (0.042)nnn 0.26 (0.114)nnn 0.39 (0.065)nnn 0.39 (0.197)nnn
Adjusted for control variables Intercept T0 T1 T2 T3 T4 Control variables Age Days of stay Gender (female as ref.) Education ( o 9 years as ref.) Marital status (TD) (not married as ref.) Physical health (TD) (good as ref.) Fairly good Poor Very poor CDR sum of boxes score (TD) PSMS sum (TD) Use of antidepressants (TD) (No users as ref.) Number of medications (TD)
1
3.52 (0.013) 0 0.97 ( o 0.001)n 0.12 (0.634)n 0.60 (0.069)n 1.29 (0.006)n
1.70 (0.022)2 0 0.41 ( o 0.001)nn 0.10 (0.395)nn 0.50 (0.001nn 0.88 (o 0.001)nn
1.61 (0.061)3 0 0.55 ( o 0.001)nnn 0.17 (0.309)nnn 0.42 (0.054)nnn 0.43 (0.157)nnn
0.03 (0.073) 2 10 4 (0.032) 0.26 (0.307) 0.13 (0.603) 0.03 (0.699)
0.01 (0.303) 8 10 5 (0.187) 0.15 (0.269) 0.04 (0.771) 0.07 (0.126)
0.02 (0.035) 1 10 4 (0.092) 0.01 (0.955) 0.16 (0.297) 0.02 (0.713)
0.84 (0.002) 1.88 ( o 0.001) 3.56 ( o 0.001) 0.23 ( o 0.001) 0.04 (0.097) 0.85 ( o 0.001) 0.18 ( o 0.001)
0.15 (0.235) 0.40 (0.006) 0.67 (o 0.001) 0.05 ( o0.001) 0.03 (0.011) 0.56 ( o0.001) 0.09 ( o0.001)
0.57 (0.002) 1.05 ( o 0.001) 2.08 (o 0.001) 0.18 (o 0.001) 0.001 (0.963) 0.22 (0.098) 0.06 (0.003)
TD ¼time-dependent variable, ref¼ reference category, CDR¼ clinical dementia rating, PSMS ¼physical self-maintenance scale. 1 Modified CSDD coefficient (p-value); 2 Modified CSDD mood coefficient (p-value): 3 Modified CSDD non-mood coefficient (p-value). n Change in CSDD coefficient; nnCSDD mood coefficient; nnnCSDD non-mood coefficient, compared to T0 (p-value).
studies was longitudinal. When adjusting for dementia severity in the present study, the increase in odds of “irritability” being present disappeared at T1–T3. This suggests that “irritability” could be linked to dementia and not depression. We saw the same phenomenon for “agitation” at T1 and T2, and “weight loss” at T1–4. Thus, it can be difficult to determine whether irritability, agitation and weight loss are symptoms of depression or dementia in this population. The prevalence, incidence and persistence rates were all low for “early morning awakening” in this study population. The other symptoms of sleep disruption varied more in prevalence, incidence and persistence rates. Verkaik found “disruption of sleep” to be the least prevalent depressive symptom in a nursing home study (Verkaik et al., 2009). In the present study there were no significant changes in the odds of the symptoms of sleep disruption at the CSDD being present when adjusting for the level of CDR. Sleep disturbances among older residents with or without dementia in nursing homes can be explained by several medical conditions. It is suggested that these symptoms should be considered as unspecific symptoms of depression in geriatric populations (Forsell et al., 1993; Kurlowicz et al., 2002). “Suicidal ideation”, “pessimism” and “delusions” are all included in the mood factor of the CSDD (Barca et al., 2008). The odds of these items being present at T1–4 were lower than at T0. This decrease could be related to a poorer ability to communicate in more severe dementia. However, the odds remained decreased when adjusting for CDR sum of boxes score. This may indicate that residents in later life in nursing homes have less suicidal ideation, depressive delusions and pessimism and/or reduced capacity to
express these symptoms. However, it could also be difficult to detect these symptoms in this stage of life. 4.2. Course of CSDD scores We identified a reduction in the mean total CSDD score from T0 to T1, which subsequently recovered to T0 levels by T2 before again decreasing (Fig. 2). Similar, there was an initial reduction in the mean non-mood CSDD score before subsequently increasing throughout the study. There was also an initial reduction in the mean mood CSDD score, followed by a slight increase from T1 to T2 before again decreasing through the remainder of the study. After adjusting for the control variables in the mixed model, there was a decrease in score of the total CSDD and the mood CSDD at the latest assessment. Previous studies have discussed reasons for less depressive symptoms occurring in the later stages of dementia, e.g., that the mental activity necessary for manifesting depression become severely impaired (Li et al., 2001). In the present study only 8.5% completed the follow-up period, but there did appear to be “a survivor effect”. The completers were younger, had less severe dementia, better somatic health and performed better in activities of personal living at T0 than the non-completers. Survivors in nursing homes are less prone to become depressed (Boorsma et al., 2012) or display depressive symptoms. There could be an initial Hawthorne effect (people involved in a research context can behave differently than otherwise) among patients and health professionals upon entering into this study, which might partly explain the reduction in CSDD scores at the beginning of the study. Previous studies of residents in nursing homes and
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patients in geriatric psychiatry services have discussed the placebo- and Hawthorne-effect in these populations (Banerjee et al., 2011; Roethlisberger and Discon, 1939; Sommer et al., 2009). 4.3. Variables associated with CSDD scores The present study found that poorer physical health was strongly associated with higher depression scores of the total CSDD, mood CSDD and non-mood CSDD, which is in line with some previous findings (Barca et al., 2009; Rozzini et al., 1996). However, longitudinal studies have drawn a more complex picture of the relationship between physical health and depression in nursing home settings (Barca et al., 2010; Parmelee et al., 1992; Smalbrugge et al., 2006). The study reported here employed different assessments of physical health, methodology and study population than previous reports. A higher CDR sum of boxes score was associated with higher CSDD scores (both mood and non-mood symptoms) (Table 4). There is as yet no clear consensus on whether depression is more common in patients with more severe dementia (Ballard et al., 1996a; Barca et al., 2008; Lyketsos and Olin, 2002). In a systematic literature review Verkaik et al. pointed out that there is evidence for a lack of association between the severity of Alzheimer's dementia and the prevalence of depressive symptoms or diagnosed depression (Verkaik et al., 2007). However, none of the 24 included studies in this review were carried out in a long-term care setting. Some studies have reported that depression in patients with vascular dementia is more severe and persistent than in patients with Alzheimer's dementia (Ballard et al., 1996a; Ballard et al., 1996b; Li et al., 2001). In the present analysis we were unfortunately unable to analyse the association between specific types of dementia and depression. Previous longitudinal studies in the nursing home settings are conflicting on whether the severity of dementia or cognitive impairment predicts depression (Barca et al., 2010; McSweeney and O’Connor, 2008; Rozzini et al., 1996). The present study differs from previous studies by using mixed model methodology and having a longer follow-up period. In the present study use of antidepressants was associated with higher depression score of the mood CSDD and total CSDD. This finding is in line with the previous results in the same sample after 12 months (Barca et al., 2010). It has previously been reported that residents in geriatric psychiatry wards in nursing homes taking antidepressants showed more depressive symptoms than residents not taking antidepressants (Verkaik et al., 2009). The residents who were taking antidepressants in the present study used adequate doses; the DDD varied between 0.8 and 1.0 during the follow-up period. It could be that many of the treated residents were non-responders. This view is supported by a systematic review of the treatment of depression in dementia (Bains et al., 2002). Also, the residents using antidepressants could have more severe depression that is difficult to treat. (Bergh et al., 2012). 4.4. Limitations This study has limitations. The methodology has not allowed the residents to be diagnosed with neither depression nor dementia according to ICD-10 or DSM-IV. We therefore relied on assessment by CDR to evaluate dementia, CDR can be considered a valid tool for this purpose among nursing home residents (Nygaard and Ruths, 2003). The use of the CSDD usually includes a clinician's interview with the patients, which did not happen in our study or in some other studies (Gruber-Baldini et al., 2005; Teresi et al., 2001). In our sample 33.7% of participants had severe dementia at baseline, and it could be difficult to rely on information obtained in a short interview with such residents. Therefore, it was decided
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to rely solely on proxy information. This could have implications for the generalization of the results (Towsley et al., 2012). Depressive symptoms in patients with dementia can show an intermittent course (Wetzels et al., 2010). In our sample of nursing home residents, in which more than 80% had dementia, depressive symptoms would ideally have been monitored more frequently than was performed. The large sample, prospective design, long follow-up period and use of well-established scales applied by educated assessors are major strengths of our study. The study included virtually all eligible residents with nursing homes stays of more than 14 days during the study period. Only two residents declined to participate and we were able to account for all residents at the follow-up assessments.
5. Conclusion This 74-month study showed that the severity of depression as measured by CSDD decreased when adjusting for relevant control variables. Poorer somatic health, higher number of medications, more severe dementia and use of antidepressants were associated with higher depression score on the CSDD. “Irritability” was the most prevalent, incident and persistent symptom of the CSDD. The lower odds of the mood symptoms “suicidal ideation”, “pessimism” and “delusions” being prevalent after baseline persisted even after adjusting for severity of dementia. This study adds important knowledge about the long-term course of depressive symptoms and depression as measured by the CSDD in nursing homes and underlines the importance to pay close attention to the overlap between depression and dementia symptoms when evaluating depression in this setting. Future research should aim at clarifying the concept of depression in the context of severe dementia for nursing home residents. There is a need of large-scale longitudinal studies of depression with frequent assessments, and stratifying the residents according to the individual subtypes of dementia.
Role of funding source The study was funded by unrestricted grants from the South-Eastern Norway Regional Health Authority and Innlandet Hospital Trust. These institutions had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report and in the decision to submit the paper for publication.
Conflict of interest Tom Borza is currently receiving PhD grant from the South-Eastern Norway Regional Health Authority and Innlandet Hospital Trust. For the remaining authors none were declared.
Acknowledgement None.
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Research report
The course of depressive symptoms as measured by the Cornell scale for depression in dementia over 74 months in 1158 nursing home residents Tom Borza a,b,n, Knut Engedal c, Sverre Bergh a, Maria Lage Barca c, Jūratė Šaltytė Benth a,d,e, Geir Selbæk a,c,d a
Centre for Old Age Psychiatric Research, Innlandet Hospital Trust, Ottestad, Norway Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway Norwegian National Advisory Unit on Aging and Health, Vestfold Health Trust, Tønsberg, Norway d Institute of Clinical Medicine, Campus AHUS, University of Oslo, Norway e HØKH, Research Centre, Akershus University Hospital, Norway b c
art ic l e i nf o
a b s t r a c t
Article history: Received 29 August 2014 Received in revised form 21 December 2014 Accepted 24 December 2014 Available online 31 December 2014
Background: Depressive symptoms and depression are common in nursing home residents. However, longitudinal studies of depression in nursing home residents are scarce and the sample sizes are small. This study aimed to investigate the course of depressive symptoms as measured by the Cornell Scale for Depression in Dementia (CSDD) and associated explanatory demographic and clinical variables. Methods: A longitudinal study over 74 months of 1158 nursing home residents aged 50 years and older from twenty six nursing homes in Norway where data was collected at five time points. Results: “Irritability” was the most prevalent, incident and persistent CSDD symptom. Compared with the baseline assessment, the likelihood of the mood symptoms “suicidal ideation,” “pessimism” and “delusions” being present was lower at all subsequent assessments. This persisted after adjusting for the severity of dementia. The severity of depression as measured by CSDD decreased over 74 months when adjusting for relevant resident variables. Poorer physical health, higher number of medications, more severe dementia and use of antidepressants were associated with higher depression score. Limitations: Depression and dementia were not diagnosed according to standardized diagnostic criteria. The use of CSDD did not include a clinician's interview with the patient. This could have implications for the generalization of the results. Conclusion: This study adds important knowledge about the long-term course of depressive symptoms and depression for residents in nursing homes, and underlines the importance to pay close attention to the overlap between depression and dementia symptoms when evaluating depression in this setting. & 2014 Elsevier B.V. All rights reserved.
Keywords: Depression Nursing home Longitudinal study Dementia
1. Introduction Depression is common in nursing home residents (Jongenelis et al., 2004). Median prevalence of major depressive disorder is 10% and median prevalence of depressive symptoms is 29% among older adults in long-term care, according to a recent systematic review (Seitz et al., 2010). Incidence rates of depression among institutionalized patients followed for 6–14 months vary between 1.8% and 14.9% (Barca et al., 2010; Boorsma et al., 2012; Katz et al., 1989; Parmelee et al., 1992; Payne et al., 2002; Smalbrugge et al., 2006). Persistence rates of clinically significant depressive symptoms vary between 44.8% and 63.3% (Barca et al., 2010; Smalbrugge et al.,
n
Corresponding author. Tel.: þ 47 91799639; fax: þ 47 62581401. E-mail address: [email protected] (T. Borza).
http://dx.doi.org/10.1016/j.jad.2014.12.053 0165-0327/& 2014 Elsevier B.V. All rights reserved.
2006) and show that depressive symptoms may follow a chronic course. The prevalence of dementia among nursing home residents varies between 63.9% and 81.0% (Selbaek et al., 2007; Wancata et al., 2003). Depression and dementia commonly coexist (McSweeney and O'Connor, 2008) and depression may present differently in patients with dementia compared to patients without dementia. New diagnostic criteria for depression in dementia have been suggested (Olin et al., 2002b). The Cornell Scale for Depression in Dementia (CSDD) has been validated for patients with and without dementia and is widely used in clinical practice and research, making CSDD a useful tool for assessing depression among nursing home residents (Alexopoulos et al., 1988a, b; Snowdon, 2010). As previous research indicates that the symptom profile of depression in dementia may differ from depression without dementia (Li et al., 2001; Olin et al., 2002b), the course of individual
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depressive symptoms in nursing home residents is of particular interest. Longitudinal studies of depression in nursing home residents are scarce and the sample sizes are small. Some of these longitudinal studies have shown that variables such as poor physical health (Rozzini et al., 1996), cognitive impairment (McSweeney and O'Connor, 2008), functional disability (Parmelee et al., 1992), a higher depression score at baseline, a shorter stay in the nursing home (Barca et al., 2010) and more years of education (Smalbrugge et al., 2006) are associated with more severe depression. One study in a highly specialized long-term care facility found a decline in depression during the first year after admission (Payne et al., 2002). However, results from longitudinal studies are conflicting regarding whether and how the variables described above are related to depression (Barca et al., 2010; Boorsma et al., 2012; McSweeney and O'Connor, 2008; Parmelee et al., 1992; Payne et al., 2002; Rozzini et al., 1996; Smalbrugge et al., 2006). We could not find any longitudinal study on depression in nursing home residents with a follow-up period of more than 14 months and no longitudinal study have investigated the course of the individual symptoms of depression. Here, we report the results of a longitudinal study including 1158 nursing home residents aged Z 50 years. The study assessed the course of individual depressive symptoms at five time points during 74 months follow-up and investigated whether the level of dementia influenced the prevalence and course of CSDD symptoms. Furthermore, we investigated which other demographic and clinical variables correlated with depression as measured by the CSDD.
2. Methods This study is a Norwegian longitudinal nursing home study. Baseline data describing the frequency of depressive symptoms and its correlates (Barca et al., 2008, 2009), as well as 12-month follow-up data examining the prevalence, incidence and persistence rates of clinically significant depressive symptoms have been published previously (Barca et al., 2010). 2.1. Participants All eligible residents in 26 nursing homes in four Norwegian counties were asked to participate. Nursing homes were selected in order to reflect the distribution of the entire nursing home population in the four counties (Selbaek et al., 2008). A minimum stay of 14 days was required for inclusion in the study. A total of 1165 patients were eligible, of which two were not willing to participate and five were excluded due to age o50 years, leaving 1158 patients in the study. The mean length of nursing home stay at the baseline assessment (T0) was 941 (SD ¼1014) days. The residents were then assessed after 12 (T1), 31 (T2), 53 (T3) and 74 months (T4) (see Fig. 1 for attrition from T0 to T4). The mean follow-up times were: 354 days (SD ¼ 15) from T0 to T1; 934 days (SD ¼34) from T0 to T2; 1580 days (SD ¼ 42) from T0 to T3; and 2232 (SD ¼79) days from T0 to T4. 2.2. Data collection Sixteen research nurses used a standardized interview and collected data from November 2004 to September 2011. Data was collected from the residents' records and interviews with residents' primary carers, who were all registered nurses. All research nurses attended a training program on how to conduct the interview, prior to all assessments. The CSDD was used to rate depressive symptoms in detail. The CSDD consists of 19 items which are rated 0 (no symptoms), 1 (mild symptoms) or 2 (severe
symptoms) and also allows a rating “item unable to evaluate”. For analyses on the course of the depressive symptoms, the 19 CSDD items were dichotomised to present (1 or 2) or absent (0). Previous research has shown that the items of the CSDD can be divided into a mood factor (anxiety, sadness, suicidal ideation, poor selfesteem, pessimism and delusion) and a non-mood factor (lack of joy, irritability, agitation, retardation, loss of interest, appetite loss, weight loss, lack of energy, diurnal variation, difficulty falling asleep, multiple awakening and early morning awakening) (Barca et al., 2008). Before calculating the sum scores of the CSDD (total, mood and non-mood CSDD scores), the rating “item unable to evaluate” was replaced by a score of 0. This method of imputation is in line with what has been recommended in previous research (Leontjevas et al., 2012). However, the CSDD scores were only calculated where at most 20% of the CSDD items had the rating “item unable to evaluate.” We used the Clinical Dementia Rating scale (CDR) to assess the severity of dementia (Hughes et al., 1982). The global score of this six-item instrument is generated using an algorithm giving precedence to memory, and the scoring ranges from 0 (no dementia) to 3 (severe dementia). In the analysis we also present the CDR sum of boxes score (which carries a maximum score of 18, where a higher score denotes more severe dementia) which has been shown to be highly correlated with the global CDR score (O'Bryant et al., 2008). In the baseline sample (n ¼1158) the (Spearman's) correlation coefficient between the CDR global score and CDR sum of boxes score was 0.93. The Physical Self-Maintenance Scale (PSMS) (Lawton and Brody, 1969) was used to assess the residents' ability to perform the personal activities of daily living. PSMS consists of six items and a higher score denotes greater impairment (maximum possible score of 30). Physical health was rated with the General Medical Health Rating scale (GMHR), a four-point (good, fair, poor, very poor) global rating scale for medical comorbidity. The GMHR takes into account each patient's number of general medical conditions, the severity of those conditions and the use of medications (Lyketsos et al., 1999). Demographic data, the residents' diagnoses and regular medication were collected from medical records. We classified the medication according to the Anatomical Therapeutic Chemical classification system (ATC) (WHO, 2014). To analyse the dose of antidepressants we used Defined Daily Dose (DDD), a World Health Organization statistical measure of drug consumption that gives the assumed average maintenance dose per day for a drug used for its main indication in adults (WHO, 2014). 2.3. Statistical analysis The following definitions were used in all analyses: prevalence (point prevalence) is the proportion of residents with the symptom present at an individual assessment; cumulative prevalence is the proportion of residents with the symptom present at at least one of the five assessments; incidence rate is the ratio of residents who presented the symptom at one assessment to those who were symptom free at the preceding assessment; persistence rate is the ratio of residents who presented the symptom at one assessment to those who presented the symptom at the preceding assessment. Data was analysed using the Statistical Program for Social Science package (SPSS v. 22.0) and Statistical Analysis System (SAS v. 9.3). Differences in clinical and demographic characteristics between completers and non-completers were analysed by independent sample t-test. Days of stay was symmetrised by a logarithmic transformation before applying t-test. For categorical data the χ2-test was employed. Time trend in the 19 depressive symptoms dichotomized to present or absent was assessed by a logistic regression model for repeated observations. As the observations also exhibited a hierarchical structure with residents nested within a ward and the
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Fig. 1. Flow chart describing attrition from T0 to T4.
wards nested within a nursing home, a three-level logistic regression model with random intercepts was estimated (SAS GLIMMIX procedure). Such a model adjusts estimated odds ratios (OR) for intra-resident correlations appearing due to repeated measurements within different levels of hierarchy. Both linear and secondorder time components were included as fixed effects. A secondorder component was only left in the model if significant. Baseline was chosen as the reference time point so that OR represents the change in time with respect to baseline. Crude ORs were further adjusted for the CDR sum of boxes score observed simultaneously with depressive symptoms. Interaction between time and CDR sum of boxes score was also assessed, but was not significantly different from 0 in all models and therefore excluded. A three-level linear mixed model (SAS MIXED procedure) with random intercepts for residents nested within wards and wards nested within nursing homes was fitted for assessing the time trend in depression scores (total CSDD, mood CSDD and non-mood CSDD). Dummies for each time point were included in the model as fixed effects with baseline as reference, capturing a non-linear nature of time trend in depression scores. Regression coefficients are to be interpreted as average change in CSDD score from baseline to a certain time point. Time trend estimates were further adjusted for age, days of stay, gender, education, marital status, physical health, CDR sum of boxes score, PSMS score, use of antidepressants and number of medications. In addition, a three-level growth model with random intercepts for residents nested within wards and wards nested within nursing homes was also estimated to assess time change in CDR sum of boxes score. We considered a p-value o0.05 as statistically significant.
2.4. Ethical and legal considerations Information about the study was given to the residents and their family members. Explicit consent was not required for enrolment, but the residents or their next of kin were informed
that they could refuse to participate at any stage of the study. The Regional Ethics Committee, the Data Inspectorate and the Directorate for Health and Social Affairs approved this procedure.
3. Results The clinical and demographic characteristics of the sample at different time points (T0–T4) are shown in Table 1. The DDD of antidepressants varied between 0.8 (SD ¼ 0.5) and 1.0 (SD ¼0.5). Of the 1158 patients, 98 (8.5%) completed T4 (completers). The completers were younger, had less severe dementia, better physical health and performed better in activities of daily living at T0 than the non-completers. At T0, 80.5% of the total sample had dementia, defined by a score Z1 on the CDR scale, 33.7% had severe dementia (CDR score¼3). The severity of dementia increased during follow-up, as the CDR-sum of boxes score increased non-linearly in time (both first- and second-order time components were significant [p o0.001]). The prevalence, incidence and persistence rates of individual CSDD symptoms are presented in Table 2. “Irritability,” “multiple physical complaints,” “anxiety,” and “sadness” had a cumulative prevalence of more than 70%, whereas “early morning awakening” and “weight loss” had a cumulative prevalence of less than 30%. The incidence rates of “irritability”, “multiple physical complaints”, “anxiety” and “sadness” were higher than 20% at at least three of the four time intervals. The incidence rates of “suicidal ideation”, “early morning awakening”, “delusions”, and “poor self-esteem” were lower than 10% at at least three of the four time intervals. “Irritability”, “anxiety” and “sadness” had persistence rates of Z 50% at all time intervals. The persistence rates of “early morning awakening” were lower than 25% at all time intervals. Table 3 presents the changes in OR of the individual CSDD symptoms being present during follow-up. Compared to T0 the odds of symptoms being present at later time points increased for: “lack of joy” at T3 and T4; “irritability” at T1–3; “agitation” at T1 and
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Table 1 Demographic and clinical characteristics of the study sample at T0–T4.
Age in years – mean (SD) Female gender (%) Education, o 9 years (%) Married (%) Days of stay – mean (SD) CSDD – mean (SD) CDR Z 1 (%)n CDR, sum of boxes score – mean (SD) Physical health (GMHR poor or very poor) (%) Number of drugs – mean (SD) Use of psychotropic drugs (%) Use of antidepressants (%) Defined daily dose of antidepressants – mean (SD) PSMS sum – mean (SD)
T0 (n ¼1158)
T1 (n¼ 786)
T2 (n¼ 394)
T3 (n¼ 209)
T4 (n¼ 98)
84.5 (7.3) 72.7 74.7 18.9 941 (1014) 5.4 (5.2) 80.5 11.3 (5.3) 48.5 6.0 (3.0) 72.9 38.1 1.0 (0.5) 18.1 (5.4)
85.0 (7.4) 74.8 74.3 17.9 1306 (1044) 4.7 (4.5) 83.8 11.9 (5.3) 46.8 6.8 (3.2) 71.5 37.3 1.0 (0.5) 18.8 (5.3)
86.4 (7.4) 75.4 75.7 15.5 1890 (1165) 5.4 (4.5) 83.6 12.3 (5.3) 46.4 6.4 (3.4) 70.6 36.5 1.0 (0.5) 19.8 (5.2)
87.6 (7.5) 76.6 75.5 13.5 2519 (1175) 5.2 (4.5) 90.7 13.5 (4.7) 51.0 6.5 (3.3) 69.4 35.4 0.8 (0.5) 20.8 (5.0)
88.0 (7.8) 71.4 77.9 9.3 3006 (1470) 4.5 (3.9) 81.3 13.3 (5.1) 51.6 6.6 (3.2) 63.3 32.7 0.9 (0.5) 21.2 (5.1)
CSDD¼ Cornell scale for depression in dementia, CDR¼ clinical dementia rating, GMHR¼ the general medical health rating scale, PSMS ¼ physical self-maintenance scale, SD ¼ standard deviation. n CDRZ 1¼ residents with dementia according to CDR.
Table 2 Prevalence, incidence and persistence rates of depressive symptoms according to the Cornell Scale for Depression in Dementia (CSDD) at the different time points and intervals. Prevalence (%)
n¼ Item: Anxiety Sadness Lack of joy Irritability Agitation Retardation Multiple physical complaints Loss of interest Appetite loss Weight loss Lack of energy Diurnal variation Difficulty falling asleep Multiple awakening Early morning awakening Suicidal ideation Poor self-esteem Pessimism Delusions
Incidence (%)
Persistence (%)
T0 1158
T1 786
T2 394
T3 209
T4 98
Cum.n 98
T0–T1 786
T1–T2 394
T2–T3 209
T3–T4 98
T0–T1 786
T1–T2 394
T2–T3 209
T3–T4 98
40 34 19 41 17 24 35 19 12 8 22 17 10 24 9 10 17 28 14
39 33 17 44 17 23 34 11 15 10 15 16 12 21 7 7 13 20 10
44 34 19 47 25 27 38 13 17 9 19 18 11 25 8 8 20 20 13
35 40 30 49 17 28 52 11 20 11 16 18 12 19 6 6 12 14 11
28 28 29 43 19 18 29 12 17 14 18 24 10 19 5 4 8 11 4
72 71 55 83 58 51 78 43 42 28 53 57 39 63 26 31 48 53 37
27 23 13 27 12 16 26 9 14 9 13 11 10 17 6 5 8 11 8
31 23 15 31 21 18 25 13 17 9 18 16 10 21 7 6 13 13 11
24 30 24 32 9 17 42 7 20 11 13 17 11 12 6 4 7 10 6
16 12 24 30 16 11 20 14 12 12 20 18 8 14 6 3 6 11 3
59 56 36 68 41 50 50 20 26 32 25 38 32 34 17 31 41 47 25
63 61 43 68 50 57 65 21 21 18 18 34 16 44 24 56 60 50 30
54 58 62 69 38 65 72 43 30 25 34 24 24 39 11 31 43 35 45
50 50 40 57 28 38 39 0 41 33 8 47 20 36 0 20 30 29 13
n
Cum. ¼ Cumulative prevalence.
T2; “multiple physical complaints” at T1–4; “appetite loss” at T1–4 and “weight loss” at T1–4. When adjusting for time-dependent CDR sum of boxes score, the significant increase did not persist for “irritability”, “agitation”, “weight loss” and “lack of joy” (at T3). Compared to T0 the odds of symptoms being present at later time points decreased for: “anxiety” at T4; “loss of interest” at T1–3; “lack of energy at T1-3; “suicidal ideation” at T1–4; “pessimism at T1–4; “delusions at T1–4. When adjusting for time-dependent CDR sum of boxes score, the significant decreases persisted. Fig. 2 demonstrates the course of the mean score of the total CSDD, the mean score of the mood and the non-mood factors of the CSDD for those completing the different time points. The changes in depression scores according to the CSDD from T0 to T4 in mixed model are presented in Table 4. In the unadjusted model there was a decrease compared to T0 in total CSDD score at T1, a decrease in mood CSDD score at T1 and T4 and a decrease in non-mood CSDD score at T1. In the adjusted model there was a
decrease compared to T0 in total CSDD score at T1 and T4, a decrease in mood CSDD score at T1, T3 and T4 and a decrease in non-mood CSDD score at T1. Poorer physical health, more severe dementia and a higher number of medications were associated with more severe depressive symptoms (CSDD total score, CSDD mood and CSDD nonmood score). The use of antidepressants was associated with higher total CSDD score and mood CSDD score. Length of stay was associated with a lower total CSDD score. Lower level of functioning was associated with a lower mood CSDD score. Lower age was associated with a higher non-mood CSDD score.
4. Discussion This longitudinal study of nursing home patients with five assessments over a 74-month follow-up showed that the severity
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Table 3 Logistic regression model for hierarchical data showing crude odds ratio (OR) and OR adjusted for time-dependent clinical dementia rating (CDR) sum of boxes scores (adj) with corresponding 95% confidence interval for depressive symptoms according to the Cornell scale for depression in dementia (CSDD) at different time points: T0: n¼ 1158, T1: n¼786, T2: n¼ 393; T3: n¼ 209; and T4: n ¼98. Time point T0 is reference. Item
T1
T2
T3
T4
T1 (adj)
T2 (adj)
T3 (adj)
T4 (adj)
Anxiety1 Sadness Lack of joy1 Irritability1 Agitation1 Retardation Multiple physical complaints Loss of interest1 Appetite lost Weight loss Lack of energy1 Diurnal variation Difficulty falling asleep Multiple awakening Early morning awakening Suicidal ideation Poor selfesteem Pessimism
1.08 (0.95; 1.22) 1.02 (0.96; 1.08) 0.97 (0.84; 1.13) 1.19 (1.05; 1.34)n 1.19 (1.02; 1.38)n 1.03 (0.97; 1.10) 1.09 (1.03; 1.15)nn
1.07 (0.85; 1.34) 1.05 (0.91; 1.21) 1.08 (0.83; 1.41) 1.39 (1.11; 1.73)nn 1.35 (1.03; 1.78)n 1.09 (0.92; 1.28) 1.25 (1.09; 1.44)nn
0.88 (0.68; 1.13) 1.08 (0.84; 1.39) 1.53 (1.14; 2.04)nn 1.40 (1.08; 1.81)n 1.27 (0.94; 1.72) 1.16 (0.87; 1.53) 1.47 (1.15; 1.87)nn
0.60 (0.39; 0.92)n 1.12 (0.79; 1.58) 2.66 (1.72; 4.11)nnn 1.19 (0.78; 1.82) 0.96 (0.59; 1.58) 1.22 (0.83; 1.81) 1.71 (1.22; 2.39)nn
1.06 (0.93; 1.20) 1.01 (0.95; 1.07) 0.90 (0.77; 1.05) 1.12 (0.99; 1.28) 1.12 (0.96; 1.31) 0.98 (0.91; 1.04) 1.08 (1.02; 1.15)nn
1.02 (0.81; 1.28) 1.02 (0.88; 1.18) 0.91 (0.69; 1.20) 1.23 (0.98; 1.55) 1.16 (0.88; 1.54) 0.94 (0.79; 1.11) 1.23 (1.06; 1.42)nn
0.82 (0.63; 1.07) 1.03 (0.80; 1.33) 1.20 (0.89; 1.62) 1.18 (0.91; 1.54) 0.97 (0.71; 1.34) 0.90 (0.67; 1.20) 1.42 (1.11; 1.82)nn
0.56 (0.36; 0.87)n 1.05 (0.73; 1.49) 2.04 (1.28; 3.25)nn 0.99 (0.63; 1.53) 0.66 (0.39; 1.13) 0.86 (0.57; 1.29) 1.64 (1.16; 2.31)nn
0.72 (0.60; 0.85)nnn 1.13 (1.06; 1.20)nnn 1.10 (1.02; 1.19)n 0.80 (0.69; 0.93)nn
0.54 (0.40; 0.74)nnn 1.37 (1.16; 1.62)nnn 1.29 (1.05; 1.58)n 0.67 (0.51; 0.87)nn
0.58 (0.41; 0.81)nn 0.89 (0.50; 1.57)
0.68 (0.57; 0.81)nnn 1.08 (1.01; 1.16)n
0.47 (0.35; 0.65)nnn 1.23 (1.04; 1.46)n
0.47 (0.34; 0.67)nnn 1.42 (1.06; 1.91)n
0.71 (0.41; 1.24)
1.54 (1.09; 2.18)n 0.70 (0.52; 0.94)n
1.83 (1.13; 2.97)n 0.96 (0.59; 1.54)
1.05 (0.98; 1.12)
1.13 (0.95; 1.34)
1.23 (0.92; 1.64)
1.03 (0.96; 1.12)
1.09 (0.89; 1.33)
0.95 (0.90; 1.02)
Delusions n
p o 0.05; 1
nn
1.71 (1.29; 2.28)nn 2.12 (1.42; 3.16)nn
1.64 (1.09; 2.46)n
1.31 (0.92; 1.86) 1.45 (0.89; 2.38) 0.59 (0.44; 0.80)nn 0.76 (0.47; 1.23)
1.33 (0.89; 1.99)
1.06 (0.98; 1.15) 1.17 (0.95; 1.86) 0.77 (0.66; 0.89)nn 0.60 (0.46; 0.79)nnn 1.03 (0.97; 1.10) 1.09 (0.92; 1.29)
1.15 (0.86; 1.55)
1.22 (0.81; 1.84)
1.16 (0.83; 1.64)
1.23 (0.77; 1.99)
1.01 (0.93; 1.09)
1.02 (0.83; 1.25)
1.04 (0.73; 1.47)
1.06 (0.65; 1.72)
0.89 (0.76; 1.04)
0.81 (0.62; 1.07)
0.75 (0.51; 1.10)
0.94 (0.88; 1.00)
0.85 (0.72; 1.00)
0.76 (0.57; 1.00)
0.68 (0.46; 1.00)
0.93 (0.85; 1.03)
0.84 (0.65; 1.08)
0.74 (0.48; 1.14)
0.65 (0.36; 1.19)
0.92 (0.84; 1.02)
0.81 (0.63; 1.05)
0.70 (0.45; 1.09)
0.61 (0.33; 1.13)
0.88 (0.78; 0.98)n
0.71 (0.53; 0.95)n
0.56 (0.34; 0.91)n
0.44 (0.22; 0.88)n
0.87 (0.78; 0.97)n
0.69 (0.52; 0.93)n
0.54 (0.32; 0.88)n
0.42 (0.21; 0.84)n
0.93 (0.86; 1.01)
0.83 (0.67; 1.02)
0.72 (0.50; 1.04)
0.63 (0.38; 1.06)
0.92 (0.85; 1.00)
0.81 (0.66; 1.01)
0.70 (0.49; 1.02)
0.61 (0.37; 1.03)
0.82 (0.76; 0.89)nnn 0.90 (0.82; 0.98)n
0.61 (0.49; 0.74)nnn 0.75 (0.59; 0.96)n
0.42 (0.30; 0.60)nnn 0.62 (0.41; 0.93)n
0.30 (0.19; 0.49)nnn
0.83 0.62 0.44 0.32 (0.20; 0.53)nnn (0.77; 0.90)nnn (0.51; 0.77)nnn (0.31; 0.63)nnn 0.88 (0.80; 0.97)nn 0.72 (0.56; 0.92)nn 0.57 (0.37; 0.86)nn 0.45 (0.25; 0.81)nn
p o 0.01;
0.51 (0.29; 0.90)n
nnn
p o 0.001.
Model contains a non-linear (second-order) trend component.
7
Total CSDD Non−mood CSDD Mood CSDD
Mean CSDD score
6 5 4 3 2 1 0 0(=T0)
12(=T1)
31(=T2)
53(=T3)
74(=T4)
Time in months Fig. 2. The course of the mean total, mood and non-mood of the Cornell scale for Depression in Dementia (CSDD) scores, (and 95% confidence intervals) for those completing T0 (n¼ 1158), T1 (n¼ 786), T2 (n¼ 394), T3 (n ¼209) and T4 (n ¼98).
of depression as measured by CSDD decreased over time after adjusting for relevant demographic and clinical variables in a mixed linear model. 4.1. Individual symptoms The course of individual symptoms varied. A previous publication has proposed that “irritability” should be used as a criterion of depression in subjects with dementia as it may be regarded to
contain elements of dysphoria (Olin et al., 2002a). In the present study 80.5% of the study population had dementia at baseline. “Irritability” was the most prevalent, incident and persistent item of the CSDD. This is in line with a study in geriatric psychiatry services (Verkaik et al., 2009) and another addressing residents in nursing homes (Ballard et al., 1996a), which both show that “irritability” is highly prevalent among dementia sufferers with comorbid depression. The study populations in these two studies were somewhat different from the present, and neither of the two
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Table 4 Mixed model for change (time trend) in depression score according to the Cornell Scale for Depression in Dementia (CSDD) from T0 to T4, and adjusted for control variables. Total CSDD
Mood CSDD
Non-mood CSDD
Unadjusted Intercept T0 T1 T2 T3 T4
5.31 ( o 0.001)1 0 0.52 (0.005)n 0.39 (0.109)n 0.55 (0.087)n 0.30 (0.512)n
1.77 ( o0.001)2 0 0.26 (0.002)nn 0.04 (0.728)nn 0.26 (0.073)nn 0.68 ( o0.001)nn
3.09 (o 0.001)3 0 0.26 (0.042)nnn 0.26 (0.114)nnn 0.39 (0.065)nnn 0.39 (0.197)nnn
Adjusted for control variables Intercept T0 T1 T2 T3 T4 Control variables Age Days of stay Gender (female as ref.) Education ( o 9 years as ref.) Marital status (TD) (not married as ref.) Physical health (TD) (good as ref.) Fairly good Poor Very poor CDR sum of boxes score (TD) PSMS sum (TD) Use of antidepressants (TD) (No users as ref.) Number of medications (TD)
1
3.52 (0.013) 0 0.97 ( o 0.001)n 0.12 (0.634)n 0.60 (0.069)n 1.29 (0.006)n
1.70 (0.022)2 0 0.41 ( o 0.001)nn 0.10 (0.395)nn 0.50 (0.001nn 0.88 (o 0.001)nn
1.61 (0.061)3 0 0.55 ( o 0.001)nnn 0.17 (0.309)nnn 0.42 (0.054)nnn 0.43 (0.157)nnn
0.03 (0.073) 2 10 4 (0.032) 0.26 (0.307) 0.13 (0.603) 0.03 (0.699)
0.01 (0.303) 8 10 5 (0.187) 0.15 (0.269) 0.04 (0.771) 0.07 (0.126)
0.02 (0.035) 1 10 4 (0.092) 0.01 (0.955) 0.16 (0.297) 0.02 (0.713)
0.84 (0.002) 1.88 ( o 0.001) 3.56 ( o 0.001) 0.23 ( o 0.001) 0.04 (0.097) 0.85 ( o 0.001) 0.18 ( o 0.001)
0.15 (0.235) 0.40 (0.006) 0.67 (o 0.001) 0.05 ( o0.001) 0.03 (0.011) 0.56 ( o0.001) 0.09 ( o0.001)
0.57 (0.002) 1.05 ( o 0.001) 2.08 (o 0.001) 0.18 (o 0.001) 0.001 (0.963) 0.22 (0.098) 0.06 (0.003)
TD ¼time-dependent variable, ref¼ reference category, CDR¼ clinical dementia rating, PSMS ¼physical self-maintenance scale. 1 Modified CSDD coefficient (p-value); 2 Modified CSDD mood coefficient (p-value): 3 Modified CSDD non-mood coefficient (p-value). n Change in CSDD coefficient; nnCSDD mood coefficient; nnnCSDD non-mood coefficient, compared to T0 (p-value).
studies was longitudinal. When adjusting for dementia severity in the present study, the increase in odds of “irritability” being present disappeared at T1–T3. This suggests that “irritability” could be linked to dementia and not depression. We saw the same phenomenon for “agitation” at T1 and T2, and “weight loss” at T1–4. Thus, it can be difficult to determine whether irritability, agitation and weight loss are symptoms of depression or dementia in this population. The prevalence, incidence and persistence rates were all low for “early morning awakening” in this study population. The other symptoms of sleep disruption varied more in prevalence, incidence and persistence rates. Verkaik found “disruption of sleep” to be the least prevalent depressive symptom in a nursing home study (Verkaik et al., 2009). In the present study there were no significant changes in the odds of the symptoms of sleep disruption at the CSDD being present when adjusting for the level of CDR. Sleep disturbances among older residents with or without dementia in nursing homes can be explained by several medical conditions. It is suggested that these symptoms should be considered as unspecific symptoms of depression in geriatric populations (Forsell et al., 1993; Kurlowicz et al., 2002). “Suicidal ideation”, “pessimism” and “delusions” are all included in the mood factor of the CSDD (Barca et al., 2008). The odds of these items being present at T1–4 were lower than at T0. This decrease could be related to a poorer ability to communicate in more severe dementia. However, the odds remained decreased when adjusting for CDR sum of boxes score. This may indicate that residents in later life in nursing homes have less suicidal ideation, depressive delusions and pessimism and/or reduced capacity to
express these symptoms. However, it could also be difficult to detect these symptoms in this stage of life. 4.2. Course of CSDD scores We identified a reduction in the mean total CSDD score from T0 to T1, which subsequently recovered to T0 levels by T2 before again decreasing (Fig. 2). Similar, there was an initial reduction in the mean non-mood CSDD score before subsequently increasing throughout the study. There was also an initial reduction in the mean mood CSDD score, followed by a slight increase from T1 to T2 before again decreasing through the remainder of the study. After adjusting for the control variables in the mixed model, there was a decrease in score of the total CSDD and the mood CSDD at the latest assessment. Previous studies have discussed reasons for less depressive symptoms occurring in the later stages of dementia, e.g., that the mental activity necessary for manifesting depression become severely impaired (Li et al., 2001). In the present study only 8.5% completed the follow-up period, but there did appear to be “a survivor effect”. The completers were younger, had less severe dementia, better somatic health and performed better in activities of personal living at T0 than the non-completers. Survivors in nursing homes are less prone to become depressed (Boorsma et al., 2012) or display depressive symptoms. There could be an initial Hawthorne effect (people involved in a research context can behave differently than otherwise) among patients and health professionals upon entering into this study, which might partly explain the reduction in CSDD scores at the beginning of the study. Previous studies of residents in nursing homes and
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patients in geriatric psychiatry services have discussed the placebo- and Hawthorne-effect in these populations (Banerjee et al., 2011; Roethlisberger and Discon, 1939; Sommer et al., 2009). 4.3. Variables associated with CSDD scores The present study found that poorer physical health was strongly associated with higher depression scores of the total CSDD, mood CSDD and non-mood CSDD, which is in line with some previous findings (Barca et al., 2009; Rozzini et al., 1996). However, longitudinal studies have drawn a more complex picture of the relationship between physical health and depression in nursing home settings (Barca et al., 2010; Parmelee et al., 1992; Smalbrugge et al., 2006). The study reported here employed different assessments of physical health, methodology and study population than previous reports. A higher CDR sum of boxes score was associated with higher CSDD scores (both mood and non-mood symptoms) (Table 4). There is as yet no clear consensus on whether depression is more common in patients with more severe dementia (Ballard et al., 1996a; Barca et al., 2008; Lyketsos and Olin, 2002). In a systematic literature review Verkaik et al. pointed out that there is evidence for a lack of association between the severity of Alzheimer's dementia and the prevalence of depressive symptoms or diagnosed depression (Verkaik et al., 2007). However, none of the 24 included studies in this review were carried out in a long-term care setting. Some studies have reported that depression in patients with vascular dementia is more severe and persistent than in patients with Alzheimer's dementia (Ballard et al., 1996a; Ballard et al., 1996b; Li et al., 2001). In the present analysis we were unfortunately unable to analyse the association between specific types of dementia and depression. Previous longitudinal studies in the nursing home settings are conflicting on whether the severity of dementia or cognitive impairment predicts depression (Barca et al., 2010; McSweeney and O’Connor, 2008; Rozzini et al., 1996). The present study differs from previous studies by using mixed model methodology and having a longer follow-up period. In the present study use of antidepressants was associated with higher depression score of the mood CSDD and total CSDD. This finding is in line with the previous results in the same sample after 12 months (Barca et al., 2010). It has previously been reported that residents in geriatric psychiatry wards in nursing homes taking antidepressants showed more depressive symptoms than residents not taking antidepressants (Verkaik et al., 2009). The residents who were taking antidepressants in the present study used adequate doses; the DDD varied between 0.8 and 1.0 during the follow-up period. It could be that many of the treated residents were non-responders. This view is supported by a systematic review of the treatment of depression in dementia (Bains et al., 2002). Also, the residents using antidepressants could have more severe depression that is difficult to treat. (Bergh et al., 2012). 4.4. Limitations This study has limitations. The methodology has not allowed the residents to be diagnosed with neither depression nor dementia according to ICD-10 or DSM-IV. We therefore relied on assessment by CDR to evaluate dementia, CDR can be considered a valid tool for this purpose among nursing home residents (Nygaard and Ruths, 2003). The use of the CSDD usually includes a clinician's interview with the patients, which did not happen in our study or in some other studies (Gruber-Baldini et al., 2005; Teresi et al., 2001). In our sample 33.7% of participants had severe dementia at baseline, and it could be difficult to rely on information obtained in a short interview with such residents. Therefore, it was decided
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to rely solely on proxy information. This could have implications for the generalization of the results (Towsley et al., 2012). Depressive symptoms in patients with dementia can show an intermittent course (Wetzels et al., 2010). In our sample of nursing home residents, in which more than 80% had dementia, depressive symptoms would ideally have been monitored more frequently than was performed. The large sample, prospective design, long follow-up period and use of well-established scales applied by educated assessors are major strengths of our study. The study included virtually all eligible residents with nursing homes stays of more than 14 days during the study period. Only two residents declined to participate and we were able to account for all residents at the follow-up assessments.
5. Conclusion This 74-month study showed that the severity of depression as measured by CSDD decreased when adjusting for relevant control variables. Poorer somatic health, higher number of medications, more severe dementia and use of antidepressants were associated with higher depression score on the CSDD. “Irritability” was the most prevalent, incident and persistent symptom of the CSDD. The lower odds of the mood symptoms “suicidal ideation”, “pessimism” and “delusions” being prevalent after baseline persisted even after adjusting for severity of dementia. This study adds important knowledge about the long-term course of depressive symptoms and depression as measured by the CSDD in nursing homes and underlines the importance to pay close attention to the overlap between depression and dementia symptoms when evaluating depression in this setting. Future research should aim at clarifying the concept of depression in the context of severe dementia for nursing home residents. There is a need of large-scale longitudinal studies of depression with frequent assessments, and stratifying the residents according to the individual subtypes of dementia.
Role of funding source The study was funded by unrestricted grants from the South-Eastern Norway Regional Health Authority and Innlandet Hospital Trust. These institutions had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report and in the decision to submit the paper for publication.
Conflict of interest Tom Borza is currently receiving PhD grant from the South-Eastern Norway Regional Health Authority and Innlandet Hospital Trust. For the remaining authors none were declared.
Acknowledgement None.
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