Research Investigation
Patient Mood and Instrumental Activities of Daily Living in Alzheimer Disease: Relationship Between Patient and Caregiver Reports
Journal of Geriatric Psychiatry and Neurology 1-7 ª The Author(s) 2015 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/0891988715588829 jgpn.sagepub.com
Kristen L. Votruba, PhD1, Carol Persad, PhD1,2, and Bruno Giordani, PhD1,2
Abstract This retrospective study investigated the relationship between self-reports and caregiver perceptions of patients’ depressive symptoms and the respective ability of these reports to predict instrumental activities of daily living (IADLs) beyond what is accounted for by cognitive abilities in 71 patients with mild Alzheimer disease. Patients completed the Geriatric Depression ScaleShort Form, and caregivers completed the Behavior Rating Scale for Dementia assessing their perception of patients’ depressive symptoms. Caregivers also completed IADL items from the Alzheimer’s Disease Cooperative Study Activities of Daily Living Inventory. Cognitive measures included the Mini-Mental State Examination, Logical Memory from the Wechsler Memory Scale III, and Trail Making Test, Part B. The relationship between self-reported depressive symptoms and caregiver report of patients’ depressive symptoms showed a trend toward significance (r ¼ .22, P ¼ .06). Measures of depressive symptoms significantly predicted 12.5% of the variance in IADLs performance, beyond that accounted for by patient demographics and cognitive functioning. Interestingly, patients’ reports, rather than caregivers’, were particularly useful in this prediction. Keywords geriatric depressive symptoms, Alzheimer disease, IADLs, self-report, caregiver report
Alzheimer disease (AD) is the most common cause of dementia in older Americans, with effects on cognition, mood, and functional abilities. It has been reported that up to 50% of individuals older than 85 years have clinical signs of the disease.1 The most common clinical sign in AD is poor recent memory.2-4 Other cognitive functions that may be impaired include language, attention, and executive functioning. These cognitive deficits are thought to limit patients’ ability to complete activities of daily living (ADLs) and instrumental ADL (IADLs)5-8 that can increase the need for health care services and place a burden on the caregivers.9,10 Patients with AD also often present with dysregulation of mood,11 with estimates of prevalence ranging from 20% to 51%.12-14 Major depressive symptoms often contribute to adverse health outcomes15-20 and impair functional abilities21-24 even in healthy adults. The presence of dementia may compound the effects that depressive symptoms have on performance of ADL and IADL. Several studies have documented a relationship between cognitive impairment, depressive symptoms, and IADL disability.21-23 Caregiver reports of functional impairment in dementia are related to both the severity of cognitive deficits and the presence of depressive symptoms in patients.25 Further, Kiosses and Alexopoulos26 showed greater impairments in performance of IADLs such as shopping for
groceries and preparing meals in patients with cognitive deficits in combination with depressive symptoms as opposed to patients with cognitive deficits alone. However, not all studies have shown an interaction between depressive symptoms and dementia, with some studies showing no differences between depressed and nondepressed AD patients’ cognitive deficits or ability to complete ADLs.13,27
Current Measurement of Depression and Capacity of Depression Rating Scales to Predict Functional Ability Current methods of assessment of depressive symptoms in patients with dementia include clinical interview, self-report, 1
Department of Psychiatry, Neuropsychology Section, University of Michigan Medical Center, Ann Arbor, MI, USA 2 Michigan Alzheimer’s Disease Center (MADC), Ann Arbor, MI, USA Corresponding Author: Kristen L. Votruba, Department of Psychiatry, Neuropsychology Section, University of Michigan, 2101 Commonwealth Blvd, Suite C, Ann Arbor, MI 48105, USA. Email: [email protected]
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and caregiver questionnaires. Most research concludes that patients with dementia perceive themselves as less depressed than do their caregivers or clinicians.28-30 Mackenzie and colleagues31 found that in their sample of 36 patients with probable or possible AD, patients yielded a depression rate of 13.9%, whereas information from their families indicated that the rate was 50.0%. This disagreement reflected greater family endorsement of patients’ loss of interest in activities, irritability, and feelings of worthlessness. Regardless of the source of the report, depressive symptoms have the potential to exacerbate the impairment in daily functioning that patients with cognitive decline may have. Therefore, it is important to determine the usefulness of patient self-reports and caregiver perceptions of patient mood as predictors of functional ability in order to employ appropriate treatment recommendations and help ensure that patient safety is maintained and independence is maximized. This retrospective study investigated the relationship between self-reported depressive symptoms in a group of patients with mild AD and their caregivers’ perceptions of the patient’s depressive symptoms. In addition, the ability of these 2 types of measurement was compared with regard to their ability to predict caregiver ratings of patients’ ability to perform IADLs over and above what could be accounted for by patient demographics and cognitive dysfunction.
Methods Participants Participants included 71 older adults who initially presented at the University of Michigan Department of Neurology and agreed to be part of a research registry through the Michigan Alzheimer’s Disease Center (MADC). Participants were diagnosed with AD at a consensus meeting consisting of at least 1 neuropsychologist and 2 neurologists. Diagnoses were made according to National Institute of Neurological and Communicative Disorders and Stroke—Alzheimer Disease and Related Disorders Association criteria, which are used in the National Institute on Aging funded National Alzheimer Coordinating Center Unified Data Set.32,33 Patients later participated in neuropsychological testing. Only patients with mild AD (Mini-Mental State Examination [MMSE] ¼ 17-23) were included in these analyses in order to control for the possibility of severe cognitive impairment that would hinder self-report accuracy. Further, based on the MADC study enrollment criteria, patients were excluded if they had a significant psychiatric history (ie, Hamilton Depression Rating Scale scores greater than 12 or significant history of psychopathology as noted during evaluation) or experienced medical or neurological deficits other than AD that may impair cognitive ability. Although those with significant motor disease (ie, Parkinson disease) were excluded, those with physical limitations, such as arthritis, were not excluded. The mean age of the sample was 71.5 years (standard deviation [SD] ¼ 10.0) with a mean education of 14.2 years (SD ¼ 2.8).
Procedure Per MADC protocol, participants underwent a neuropsychological battery that included measures of memory, executive functioning, mental status, and mood. Only results from the participants’ first neuropsychological evaluation were included in these analyses. Caregivers (who all reported having ‘‘regular’’ contact with the participant) filled out questionnaires assessing their perception of the patient’s mood and ability to complete IADLs. Although direct observations of daily activities would be preferable, the cost and time associated with such analyses are extensive and so caregiver ratings were instead utilized.
Measures Caregiver questionnaires Behavior Rating Scale for Dementia from the Consortium to Establish a Registry for Alzheimer Disease. This is a standardized instrument for caregiver ratings of behavioral abnormalities in cognitively impaired individuals.34 The scale consists of 46 items, which can be categorized into clinically relevant domains, that is, depressive features, psychotic symptoms, behavioral dysregulation, irritability/agitation, vegetative features, aggression, and affective lability that are evaluated on a Likert-type scale to determine the frequency of various behaviors. The measure of depressive symptoms was used in these analyses in order to evaluate caregivers’ perception of true depressed mood as opposed to their perception of somatic symptoms that may accompany the disease state. The depression subscale is composed of 7 items with higher scores indicating more depressive symptom endorsement. The Behavior Rating Scale for Dementia (BRSD) depression scale has been shown to have high internal consistency (a ¼ .77). IADL questions from the Alzheimer Disease Cooperative Study activities of daily living inventory. This informant rating scale estimates a patient’s ability to complete daily activities.35 It includes questions related to ADLs such as a patient’s ability to eat, dress, bathe, and ambulate and questions related to IADLs, such as hobbies, writing, and use of household appliances. The latter IADLs questions were used in these analyses with scores ranging from 0 to 10. Higher scores on the Alzheimer Disease Cooperative Study scale indicate more difficulty completing IADLs; thus, a ‘‘perfect score’’ would be indicated by a score of zero. Patient evaluations Mini-Mental State Examination. The MMSE is a brief test of basic cognitive functions relating to major cognitive domains such as orientation, attention, memory, language, and visual– spatial abilities.36 Scores below 24 are considered abnormal. The MMSE is currently the most commonly used brief screening measure for dementia.37 Wechsler Memory Scale—III (Logical Memory II subtest). The Logical Memory Test is a memory test in which participants
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are asked to recall short stories that are read to them immediately and then recall these stories 30 minutes later (ie, delayed recall).38 The delayed recall memory score was used in these analyses with a total score ranging from 0 to 50. Trail Making Test, Part B. It is a test of conceptual ability and visuomotor tracking that requires a participant to consecutively connect alternating numbered and lettered circles as quickly as possible.37 Time to complete Part B of the Trail Making Test is used as a measure of executive functioning abilities.39 Higher scores reflect worse performance on this test. Geriatric Depression Scale—Short Form. The 15-item version of the Geriatric Depression Scale (GDS) was developed for use in older medically ill populations or those with dementia, with scores above 4 considered significant for clinical symptoms of depression.40 This measure that uses a simple yes/no response has been shown to be reliable and valid in a sample of individuals with mild AD, with an internal consistency of .84 and strong correlations with other measures of depressive symptoms.41
Statistical Analyses Prior to analyses, all variables were screened for violations of the assumptions associated with univariate and multivariate tests. Variables with nonnormal distributions that could inflate a were transformed to improve normality and linearity, and univariate outliers were windsorized according to the procedures recommended by Tabachnik and Fidell.42 As analyses for both the raw and the transformed variables produced equivalent results, the raw data are listed in the table for ease of interpretation but the transformed variables were used in analyses. Correlational analyses evaluated the relationship between patients’ self-reported depressive symptoms and their caregiver’s perception of their symptoms. Hierarchical regressions were used to determine the predictive ability of the cognitive tasks and measures of depressive symptoms on caregiver ratings of patients’ ability to complete IADLs. Age, education, and mental status were first entered into the regression, followed by the cognitive measures. The measures of depressive symptoms were always entered on the last step.
Results Table 1 lists the descriptive statistics for the variables of interest in this study, including measures of caregiver report of IADL functioning, cognitive testing performance, and self-reported and informant-reported symptoms of patient depressive symptoms. Based on the findings, this sample would be classified as having mild dementia (mean MMSE ¼ 19.86), with significant impairment in both delayed recall and executive functioning. In general, there was a low (insignificant) rate of depressive symptom endorsement from patients and a high rate of endorsement of patient depressive symptoms by the patients’ caregivers.
Table 1. Descriptive Statistics. Measure IADLs MMSE LM II delayed recall (raw) Trails B, seconds BRSD-depressive GDS
Sample Mean
Standard Deviation
2.23 19.86 4.28 342.42 59.25 2.85
2.06 1.99 5.28 119.54 20.54 2.21
Abbreviations: BRSD, Behavior Rating Scale for Dementia; GDS, Geriatric Depression Scale; IADLs, instrumental activities of daily living; LM, Logical Memory; MMSE, Mini-Mental State Examination.
Table 2. Correlations Among Variables of Interest. IADLs Age Age .084 – Education .133 .031 MMSE .257a .093 LM II .071 .189 Trails B .355b .120 BRSD .240a .101 GDS .319b .166
Education MMSE LM II Trails B BRSD – .167 .050 .049 .144 .272a
– .225 – .503b .080 .182 .032 .112 .033
– .159 .234a
– .224
Abbreviations: BRSD, Behavior Rating Scale for Dementia; GDS, Geriatric Depression Scale; IADLs, instrumental activities of daily living; LM, Logical Memory; MMSE, Mini-Mental State Examination. a P < .05. b P < .01.
Table 2 lists the correlations among variables of interest, including demographic variables, cognitive abilities, and measures of patients’ depressive symptoms. As has been found in previous studies, self-reported depressive symptoms were not significantly correlated with caregiver reports of patients’ depressive symptoms (r ¼ .224, P ¼ .06), although there was a trend in this direction. It does not appear that caregivers overestimated patient’s depressive symptoms as a result of the patient’s overall cognitive functioning, as the correlation between the patient’s MMSE score and the caregiver’s perception of patient depressive symptoms was also not significant (r ¼ .182; P ¼ .13). Both the self-report and informant report of depressive symptoms positively correlated significantly with IADL performance (r ¼ .319, P < .01 and r ¼ .240, P < .05, respectively). Because lower scores on the IADL measure indicate better performance, the positive correlations indicate that the more depressive symptoms that were endorsed, the poorer the performance on measures of IADLs. Similarly, performance on tests of global mental status (MMSE; r ¼ .257, P < .05) and executive functioning (trails B; r ¼ .355, P < .01) correlated significantly with IADLs in the expected directions indicating that more cognitively intact individuals are more able to complete IADLs. This study also found that as education increases, the probability of self-reported depressive symptoms decreases (r ¼ .272, P < .05). After controlling for cognitive abilities, this relationship became even stronger (r ¼ .353, P < .01), which suggests that education may be a protective factor against depressive symptoms in patients
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Table 3. Hierarchical Regression With IADLs as the Dependent Variable. Variables Model 1 Age Education MMSE Model 2 Age Education MMSE LM delayed recall Trails B Model 3 Age Education MMSE LM delayed recall Trails B, seconds BRSD-depressive GDS—SF
R2 Change
F Change
df
Sig
.109
2.73
3.67
.051
.072
.125
2.87
5.69
2.65
2.63
Stand. b
t
Sig
sr2
.11 .18 .3
0.92 1.53 2.52
.363 .13 .014
.01 .03 .08
.15 .14 .19 .11 .26
1.3 1.22 1.33 0.94 1.95
.199 .225 .188 .352 .056
.02 .02 .02 .01 .05
.2 .25 .2 .11 .16 .15 .33
1.87 2.23 1.51 1.01 1.2 1.38 2.8
.066 .029 .137 .319 .233 .173 .007
.04 .05 .02 .01 .02 .02 .09
.064
.005
Abbreviations: BRSD, Behavior Rating Scale for Dementia; GDS-SF, Geriatric Depression Scale Short Form; LM, Logical Memory; IADLs, instrumental activities of daily living; MMSE, Mini-Mental State Examination.
with AD. A similar relationship was not found for caregiver reports of patient depressive symptoms either before (r ¼ .144, P ¼ .344) or after (r ¼ .053, P ¼ .67) controlling for cognitive factors. Hierarchical multiple regressions were conducted to determine the relative contribution of self- and caregiver ratings of patient’s depressive symptoms in the prediction of caregiverrated IADLs over and above what was accounted for by the patient’s age, education, mental status, memory, and executive functioning ability. The first analysis tested a hierarchical regression with age, education, and MMSE score entered on step 1; verbal memory (Logical Memory II delayed recall) and executive functioning (trails B) entered on step 2; and BRSD-depressive scores and GDS scores added on step 3, with the IADLs score as the dependent variable. The results of this analysis are summarized in Table 3. The regression analysis showed only a trend toward significance on step 1, F3, 67 ¼ 2.73, R2 ¼ .109, P ¼ .051 and on step 2, F2, 65 ¼ 2.87, R2 ¼ .072, P ¼ .064, suggesting that the use of demographic variables, mental status, memory, and executive functioning was not sufficient to significantly predict IADLs performance. However, on step 3, results showed that adding the GDS and the BRSD-depressive scores accounted for an additional 12.5% of the variance in IADLs performance over and above that accounted for by age, education, mental status, memory, and executive functioning (F2, 63 ¼ 5.69, R2 ¼ .125, P ¼ .005). Examination of the squared semipartial correlations indicates that the GDS made a unique and significant contribution to the prediction of IADLs, accounting for 8.6% of unique variance in IADLs performance. In contrast, the caregiver’s report of patient’s depressive symptoms did not add uniquely to the prediction of IADLs (sr2 ¼ .02). Multiple regressions were then run to determine the independent contributions of self-reports and caregiver reports.
Two hierarchical regressions were run with the same first 2 steps in the model but entering either the BRSD or the GDS alone on step 3. With the BRSD alone entered on step 3, the model showed a trend toward significance, F1, 64 ¼ 3.18, R2 ¼ .039, P ¼ .079. Thus the BRSD contributed 3.9% unique variance to the prediction of IADLs. Alternatively, with the GDS entered alone on step 3, the model was significant, F1, 84 ¼ 8.54, R2 ¼ .084, P ¼ .004. Thus, the GDS contributed 8.4% unique variance to the prediction of IADLs. Finally, two 4-step models were run to see whether selfreported depressive symptoms or caregiver reports made a significant contribution, above and beyond the contribution made by the other type of report form. With the GDS entered on step 3 and the BRSD entered on step 4, only step 3 was significant (P < .01) indicating that caregiver reports did not add any information over and above the self-report measure. However, when the BRSD was added on step 3 and the GDS was added on step 4, the model was significant on step 4, F1, 63 ¼ 7.86, R2 ¼ .087, P ¼ .007, indicating that the selfreport measure added significant information above and beyond what was added by the caregiver’s report.
Discussion This study is important because it investigated whether the selfreport of depressed mood by patients with mild AD can be used to adequately predict aspects of their functional ability in contrast to ratings of their depressive symptoms by their caregivers. Clinically, little weight is often given to patient selfreport in terms of predictive utility when there is an obvious cognitive impairment, as compared to the importance afforded such self-reports when cognitive status is not in question. In contrast, more credence is given to the caregiver’s perception of the patient’s mood state and ability level when patients have
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dementia. This study questions this practice by demonstrating that, by utilizing a self-report measure and a caregiver-rated measure of patient depressive symptoms, we were able to substantially predict the ability of patients to perform IADLs over and above what is accounted for by the patient’s age, education, mental status, verbal memory, and executive functioning ability. Importantly, further analyses indicated that self-reports were more uniquely helpful in making this prediction than were caregiver reports and that the contribution of self-reports in mild AD can be extremely valuable. Although there was admittedly a restricted range of depressive symptom scores included in this study, due to enrollment exclusions (eg, exclusion of cases of major depressive disorder), self-reports of depressive symptoms were helpful in this prediction even with a very low level of symptom endorsement by patients. In cases of mild AD, it is clear that patients can assist in predicting functional abilities, and their self-reports of affective symptoms should therefore be given appropriate attention. The inability of the caregiver-rated perceptions of patient depressive symptoms to predict the caregiver-rated IADL performance was unexpected, particularly given their shared method variance. This suggests that assessing the subjective nature of mood perception may be more difficult than evaluating a person’s objective functional abilities. Similar to prior research, this study failed to find a strong relationship between self-reports and caregiver ratings of patient depressive symptoms and demonstrated that caregivers often perceive patients to be experiencing more depressive symptoms than the patient reports himself or herself.43-45 Our study did not support the hypothesis that caregiver’s ratings of depressive symptoms are a reflection of their perception of the patient’s cognitive abilities, as the patient’s overall mental status was not related to the caregiver’s ratings. However, perhaps the caregiver reports of patient’s mood may be impacted by other factors such as their own depressive symptoms or the amount of burden that they experience being a caregiver. Further assessment is needed to understand how these and other factors impact caregiver ratings of a patient’s mood and ability to engage in independent ADL. This study was limited by the restricted range of IADLs questions and the fact that our measure of IADLs was rated by the patient’s caregiver and not based specifically on patient performance. Future research could employ performancebased measures of IADLs to improve validity. Although all of the patients recruited were free of significant neurological or motor impairment, we did not have specific information regarding a patient’s potential physical disabilities such as arthritis that could impact IADL performance. Future research will also need to include ratings of physical disability in order to rule out the potential influence of physical limitations on performance of IADLs. Further, the exclusion of participants who experienced high levels of depression likely restricted our range of depressive symptomology but highlights that, even in a population with relatively low levels of depressive symptoms, patient self-reports are influential in predicting the patient’s ability to complete complex IADLs. Finally, available data
did not allow us to fully clarify the relationship between the caregiver and the patient. Although all caregivers rated their contact with the patient as ‘‘regular,’’ it is possible that the relationships in our study population varied and some caregivers were more knowledgeable than others about the current status of the patients in this sample. Further investigation of this relationship, including comparison of significant other and child ratings, may be valuable in future studies. Acknowledgments The authors thank Michelle McFadden and Tarin Coulas for their assistance in the completion of this study.
Authors’ Note Results of this study were presented at the annual meeting of the International Neuropsychological Society, February 13, 2008, Atlanta, Georgia.
Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was supported by NIH-NIA P50 AG08671 and the Michigan Alzheimer’s Disease Research Center. We would like to acknowledge the National Institute on Aging Claude Pepper Older Adults Independence Center Grant AG08808.
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Patient Mood and Instrumental Activities of Daily Living in Alzheimer Disease: Relationship Between Patient and Caregiver Reports
Journal of Geriatric Psychiatry and Neurology 1-7 ª The Author(s) 2015 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/0891988715588829 jgpn.sagepub.com
Kristen L. Votruba, PhD1, Carol Persad, PhD1,2, and Bruno Giordani, PhD1,2
Abstract This retrospective study investigated the relationship between self-reports and caregiver perceptions of patients’ depressive symptoms and the respective ability of these reports to predict instrumental activities of daily living (IADLs) beyond what is accounted for by cognitive abilities in 71 patients with mild Alzheimer disease. Patients completed the Geriatric Depression ScaleShort Form, and caregivers completed the Behavior Rating Scale for Dementia assessing their perception of patients’ depressive symptoms. Caregivers also completed IADL items from the Alzheimer’s Disease Cooperative Study Activities of Daily Living Inventory. Cognitive measures included the Mini-Mental State Examination, Logical Memory from the Wechsler Memory Scale III, and Trail Making Test, Part B. The relationship between self-reported depressive symptoms and caregiver report of patients’ depressive symptoms showed a trend toward significance (r ¼ .22, P ¼ .06). Measures of depressive symptoms significantly predicted 12.5% of the variance in IADLs performance, beyond that accounted for by patient demographics and cognitive functioning. Interestingly, patients’ reports, rather than caregivers’, were particularly useful in this prediction. Keywords geriatric depressive symptoms, Alzheimer disease, IADLs, self-report, caregiver report
Alzheimer disease (AD) is the most common cause of dementia in older Americans, with effects on cognition, mood, and functional abilities. It has been reported that up to 50% of individuals older than 85 years have clinical signs of the disease.1 The most common clinical sign in AD is poor recent memory.2-4 Other cognitive functions that may be impaired include language, attention, and executive functioning. These cognitive deficits are thought to limit patients’ ability to complete activities of daily living (ADLs) and instrumental ADL (IADLs)5-8 that can increase the need for health care services and place a burden on the caregivers.9,10 Patients with AD also often present with dysregulation of mood,11 with estimates of prevalence ranging from 20% to 51%.12-14 Major depressive symptoms often contribute to adverse health outcomes15-20 and impair functional abilities21-24 even in healthy adults. The presence of dementia may compound the effects that depressive symptoms have on performance of ADL and IADL. Several studies have documented a relationship between cognitive impairment, depressive symptoms, and IADL disability.21-23 Caregiver reports of functional impairment in dementia are related to both the severity of cognitive deficits and the presence of depressive symptoms in patients.25 Further, Kiosses and Alexopoulos26 showed greater impairments in performance of IADLs such as shopping for
groceries and preparing meals in patients with cognitive deficits in combination with depressive symptoms as opposed to patients with cognitive deficits alone. However, not all studies have shown an interaction between depressive symptoms and dementia, with some studies showing no differences between depressed and nondepressed AD patients’ cognitive deficits or ability to complete ADLs.13,27
Current Measurement of Depression and Capacity of Depression Rating Scales to Predict Functional Ability Current methods of assessment of depressive symptoms in patients with dementia include clinical interview, self-report, 1
Department of Psychiatry, Neuropsychology Section, University of Michigan Medical Center, Ann Arbor, MI, USA 2 Michigan Alzheimer’s Disease Center (MADC), Ann Arbor, MI, USA Corresponding Author: Kristen L. Votruba, Department of Psychiatry, Neuropsychology Section, University of Michigan, 2101 Commonwealth Blvd, Suite C, Ann Arbor, MI 48105, USA. Email: [email protected]
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and caregiver questionnaires. Most research concludes that patients with dementia perceive themselves as less depressed than do their caregivers or clinicians.28-30 Mackenzie and colleagues31 found that in their sample of 36 patients with probable or possible AD, patients yielded a depression rate of 13.9%, whereas information from their families indicated that the rate was 50.0%. This disagreement reflected greater family endorsement of patients’ loss of interest in activities, irritability, and feelings of worthlessness. Regardless of the source of the report, depressive symptoms have the potential to exacerbate the impairment in daily functioning that patients with cognitive decline may have. Therefore, it is important to determine the usefulness of patient self-reports and caregiver perceptions of patient mood as predictors of functional ability in order to employ appropriate treatment recommendations and help ensure that patient safety is maintained and independence is maximized. This retrospective study investigated the relationship between self-reported depressive symptoms in a group of patients with mild AD and their caregivers’ perceptions of the patient’s depressive symptoms. In addition, the ability of these 2 types of measurement was compared with regard to their ability to predict caregiver ratings of patients’ ability to perform IADLs over and above what could be accounted for by patient demographics and cognitive dysfunction.
Methods Participants Participants included 71 older adults who initially presented at the University of Michigan Department of Neurology and agreed to be part of a research registry through the Michigan Alzheimer’s Disease Center (MADC). Participants were diagnosed with AD at a consensus meeting consisting of at least 1 neuropsychologist and 2 neurologists. Diagnoses were made according to National Institute of Neurological and Communicative Disorders and Stroke—Alzheimer Disease and Related Disorders Association criteria, which are used in the National Institute on Aging funded National Alzheimer Coordinating Center Unified Data Set.32,33 Patients later participated in neuropsychological testing. Only patients with mild AD (Mini-Mental State Examination [MMSE] ¼ 17-23) were included in these analyses in order to control for the possibility of severe cognitive impairment that would hinder self-report accuracy. Further, based on the MADC study enrollment criteria, patients were excluded if they had a significant psychiatric history (ie, Hamilton Depression Rating Scale scores greater than 12 or significant history of psychopathology as noted during evaluation) or experienced medical or neurological deficits other than AD that may impair cognitive ability. Although those with significant motor disease (ie, Parkinson disease) were excluded, those with physical limitations, such as arthritis, were not excluded. The mean age of the sample was 71.5 years (standard deviation [SD] ¼ 10.0) with a mean education of 14.2 years (SD ¼ 2.8).
Procedure Per MADC protocol, participants underwent a neuropsychological battery that included measures of memory, executive functioning, mental status, and mood. Only results from the participants’ first neuropsychological evaluation were included in these analyses. Caregivers (who all reported having ‘‘regular’’ contact with the participant) filled out questionnaires assessing their perception of the patient’s mood and ability to complete IADLs. Although direct observations of daily activities would be preferable, the cost and time associated with such analyses are extensive and so caregiver ratings were instead utilized.
Measures Caregiver questionnaires Behavior Rating Scale for Dementia from the Consortium to Establish a Registry for Alzheimer Disease. This is a standardized instrument for caregiver ratings of behavioral abnormalities in cognitively impaired individuals.34 The scale consists of 46 items, which can be categorized into clinically relevant domains, that is, depressive features, psychotic symptoms, behavioral dysregulation, irritability/agitation, vegetative features, aggression, and affective lability that are evaluated on a Likert-type scale to determine the frequency of various behaviors. The measure of depressive symptoms was used in these analyses in order to evaluate caregivers’ perception of true depressed mood as opposed to their perception of somatic symptoms that may accompany the disease state. The depression subscale is composed of 7 items with higher scores indicating more depressive symptom endorsement. The Behavior Rating Scale for Dementia (BRSD) depression scale has been shown to have high internal consistency (a ¼ .77). IADL questions from the Alzheimer Disease Cooperative Study activities of daily living inventory. This informant rating scale estimates a patient’s ability to complete daily activities.35 It includes questions related to ADLs such as a patient’s ability to eat, dress, bathe, and ambulate and questions related to IADLs, such as hobbies, writing, and use of household appliances. The latter IADLs questions were used in these analyses with scores ranging from 0 to 10. Higher scores on the Alzheimer Disease Cooperative Study scale indicate more difficulty completing IADLs; thus, a ‘‘perfect score’’ would be indicated by a score of zero. Patient evaluations Mini-Mental State Examination. The MMSE is a brief test of basic cognitive functions relating to major cognitive domains such as orientation, attention, memory, language, and visual– spatial abilities.36 Scores below 24 are considered abnormal. The MMSE is currently the most commonly used brief screening measure for dementia.37 Wechsler Memory Scale—III (Logical Memory II subtest). The Logical Memory Test is a memory test in which participants
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are asked to recall short stories that are read to them immediately and then recall these stories 30 minutes later (ie, delayed recall).38 The delayed recall memory score was used in these analyses with a total score ranging from 0 to 50. Trail Making Test, Part B. It is a test of conceptual ability and visuomotor tracking that requires a participant to consecutively connect alternating numbered and lettered circles as quickly as possible.37 Time to complete Part B of the Trail Making Test is used as a measure of executive functioning abilities.39 Higher scores reflect worse performance on this test. Geriatric Depression Scale—Short Form. The 15-item version of the Geriatric Depression Scale (GDS) was developed for use in older medically ill populations or those with dementia, with scores above 4 considered significant for clinical symptoms of depression.40 This measure that uses a simple yes/no response has been shown to be reliable and valid in a sample of individuals with mild AD, with an internal consistency of .84 and strong correlations with other measures of depressive symptoms.41
Statistical Analyses Prior to analyses, all variables were screened for violations of the assumptions associated with univariate and multivariate tests. Variables with nonnormal distributions that could inflate a were transformed to improve normality and linearity, and univariate outliers were windsorized according to the procedures recommended by Tabachnik and Fidell.42 As analyses for both the raw and the transformed variables produced equivalent results, the raw data are listed in the table for ease of interpretation but the transformed variables were used in analyses. Correlational analyses evaluated the relationship between patients’ self-reported depressive symptoms and their caregiver’s perception of their symptoms. Hierarchical regressions were used to determine the predictive ability of the cognitive tasks and measures of depressive symptoms on caregiver ratings of patients’ ability to complete IADLs. Age, education, and mental status were first entered into the regression, followed by the cognitive measures. The measures of depressive symptoms were always entered on the last step.
Results Table 1 lists the descriptive statistics for the variables of interest in this study, including measures of caregiver report of IADL functioning, cognitive testing performance, and self-reported and informant-reported symptoms of patient depressive symptoms. Based on the findings, this sample would be classified as having mild dementia (mean MMSE ¼ 19.86), with significant impairment in both delayed recall and executive functioning. In general, there was a low (insignificant) rate of depressive symptom endorsement from patients and a high rate of endorsement of patient depressive symptoms by the patients’ caregivers.
Table 1. Descriptive Statistics. Measure IADLs MMSE LM II delayed recall (raw) Trails B, seconds BRSD-depressive GDS
Sample Mean
Standard Deviation
2.23 19.86 4.28 342.42 59.25 2.85
2.06 1.99 5.28 119.54 20.54 2.21
Abbreviations: BRSD, Behavior Rating Scale for Dementia; GDS, Geriatric Depression Scale; IADLs, instrumental activities of daily living; LM, Logical Memory; MMSE, Mini-Mental State Examination.
Table 2. Correlations Among Variables of Interest. IADLs Age Age .084 – Education .133 .031 MMSE .257a .093 LM II .071 .189 Trails B .355b .120 BRSD .240a .101 GDS .319b .166
Education MMSE LM II Trails B BRSD – .167 .050 .049 .144 .272a
– .225 – .503b .080 .182 .032 .112 .033
– .159 .234a
– .224
Abbreviations: BRSD, Behavior Rating Scale for Dementia; GDS, Geriatric Depression Scale; IADLs, instrumental activities of daily living; LM, Logical Memory; MMSE, Mini-Mental State Examination. a P < .05. b P < .01.
Table 2 lists the correlations among variables of interest, including demographic variables, cognitive abilities, and measures of patients’ depressive symptoms. As has been found in previous studies, self-reported depressive symptoms were not significantly correlated with caregiver reports of patients’ depressive symptoms (r ¼ .224, P ¼ .06), although there was a trend in this direction. It does not appear that caregivers overestimated patient’s depressive symptoms as a result of the patient’s overall cognitive functioning, as the correlation between the patient’s MMSE score and the caregiver’s perception of patient depressive symptoms was also not significant (r ¼ .182; P ¼ .13). Both the self-report and informant report of depressive symptoms positively correlated significantly with IADL performance (r ¼ .319, P < .01 and r ¼ .240, P < .05, respectively). Because lower scores on the IADL measure indicate better performance, the positive correlations indicate that the more depressive symptoms that were endorsed, the poorer the performance on measures of IADLs. Similarly, performance on tests of global mental status (MMSE; r ¼ .257, P < .05) and executive functioning (trails B; r ¼ .355, P < .01) correlated significantly with IADLs in the expected directions indicating that more cognitively intact individuals are more able to complete IADLs. This study also found that as education increases, the probability of self-reported depressive symptoms decreases (r ¼ .272, P < .05). After controlling for cognitive abilities, this relationship became even stronger (r ¼ .353, P < .01), which suggests that education may be a protective factor against depressive symptoms in patients
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Table 3. Hierarchical Regression With IADLs as the Dependent Variable. Variables Model 1 Age Education MMSE Model 2 Age Education MMSE LM delayed recall Trails B Model 3 Age Education MMSE LM delayed recall Trails B, seconds BRSD-depressive GDS—SF
R2 Change
F Change
df
Sig
.109
2.73
3.67
.051
.072
.125
2.87
5.69
2.65
2.63
Stand. b
t
Sig
sr2
.11 .18 .3
0.92 1.53 2.52
.363 .13 .014
.01 .03 .08
.15 .14 .19 .11 .26
1.3 1.22 1.33 0.94 1.95
.199 .225 .188 .352 .056
.02 .02 .02 .01 .05
.2 .25 .2 .11 .16 .15 .33
1.87 2.23 1.51 1.01 1.2 1.38 2.8
.066 .029 .137 .319 .233 .173 .007
.04 .05 .02 .01 .02 .02 .09
.064
.005
Abbreviations: BRSD, Behavior Rating Scale for Dementia; GDS-SF, Geriatric Depression Scale Short Form; LM, Logical Memory; IADLs, instrumental activities of daily living; MMSE, Mini-Mental State Examination.
with AD. A similar relationship was not found for caregiver reports of patient depressive symptoms either before (r ¼ .144, P ¼ .344) or after (r ¼ .053, P ¼ .67) controlling for cognitive factors. Hierarchical multiple regressions were conducted to determine the relative contribution of self- and caregiver ratings of patient’s depressive symptoms in the prediction of caregiverrated IADLs over and above what was accounted for by the patient’s age, education, mental status, memory, and executive functioning ability. The first analysis tested a hierarchical regression with age, education, and MMSE score entered on step 1; verbal memory (Logical Memory II delayed recall) and executive functioning (trails B) entered on step 2; and BRSD-depressive scores and GDS scores added on step 3, with the IADLs score as the dependent variable. The results of this analysis are summarized in Table 3. The regression analysis showed only a trend toward significance on step 1, F3, 67 ¼ 2.73, R2 ¼ .109, P ¼ .051 and on step 2, F2, 65 ¼ 2.87, R2 ¼ .072, P ¼ .064, suggesting that the use of demographic variables, mental status, memory, and executive functioning was not sufficient to significantly predict IADLs performance. However, on step 3, results showed that adding the GDS and the BRSD-depressive scores accounted for an additional 12.5% of the variance in IADLs performance over and above that accounted for by age, education, mental status, memory, and executive functioning (F2, 63 ¼ 5.69, R2 ¼ .125, P ¼ .005). Examination of the squared semipartial correlations indicates that the GDS made a unique and significant contribution to the prediction of IADLs, accounting for 8.6% of unique variance in IADLs performance. In contrast, the caregiver’s report of patient’s depressive symptoms did not add uniquely to the prediction of IADLs (sr2 ¼ .02). Multiple regressions were then run to determine the independent contributions of self-reports and caregiver reports.
Two hierarchical regressions were run with the same first 2 steps in the model but entering either the BRSD or the GDS alone on step 3. With the BRSD alone entered on step 3, the model showed a trend toward significance, F1, 64 ¼ 3.18, R2 ¼ .039, P ¼ .079. Thus the BRSD contributed 3.9% unique variance to the prediction of IADLs. Alternatively, with the GDS entered alone on step 3, the model was significant, F1, 84 ¼ 8.54, R2 ¼ .084, P ¼ .004. Thus, the GDS contributed 8.4% unique variance to the prediction of IADLs. Finally, two 4-step models were run to see whether selfreported depressive symptoms or caregiver reports made a significant contribution, above and beyond the contribution made by the other type of report form. With the GDS entered on step 3 and the BRSD entered on step 4, only step 3 was significant (P < .01) indicating that caregiver reports did not add any information over and above the self-report measure. However, when the BRSD was added on step 3 and the GDS was added on step 4, the model was significant on step 4, F1, 63 ¼ 7.86, R2 ¼ .087, P ¼ .007, indicating that the selfreport measure added significant information above and beyond what was added by the caregiver’s report.
Discussion This study is important because it investigated whether the selfreport of depressed mood by patients with mild AD can be used to adequately predict aspects of their functional ability in contrast to ratings of their depressive symptoms by their caregivers. Clinically, little weight is often given to patient selfreport in terms of predictive utility when there is an obvious cognitive impairment, as compared to the importance afforded such self-reports when cognitive status is not in question. In contrast, more credence is given to the caregiver’s perception of the patient’s mood state and ability level when patients have
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dementia. This study questions this practice by demonstrating that, by utilizing a self-report measure and a caregiver-rated measure of patient depressive symptoms, we were able to substantially predict the ability of patients to perform IADLs over and above what is accounted for by the patient’s age, education, mental status, verbal memory, and executive functioning ability. Importantly, further analyses indicated that self-reports were more uniquely helpful in making this prediction than were caregiver reports and that the contribution of self-reports in mild AD can be extremely valuable. Although there was admittedly a restricted range of depressive symptom scores included in this study, due to enrollment exclusions (eg, exclusion of cases of major depressive disorder), self-reports of depressive symptoms were helpful in this prediction even with a very low level of symptom endorsement by patients. In cases of mild AD, it is clear that patients can assist in predicting functional abilities, and their self-reports of affective symptoms should therefore be given appropriate attention. The inability of the caregiver-rated perceptions of patient depressive symptoms to predict the caregiver-rated IADL performance was unexpected, particularly given their shared method variance. This suggests that assessing the subjective nature of mood perception may be more difficult than evaluating a person’s objective functional abilities. Similar to prior research, this study failed to find a strong relationship between self-reports and caregiver ratings of patient depressive symptoms and demonstrated that caregivers often perceive patients to be experiencing more depressive symptoms than the patient reports himself or herself.43-45 Our study did not support the hypothesis that caregiver’s ratings of depressive symptoms are a reflection of their perception of the patient’s cognitive abilities, as the patient’s overall mental status was not related to the caregiver’s ratings. However, perhaps the caregiver reports of patient’s mood may be impacted by other factors such as their own depressive symptoms or the amount of burden that they experience being a caregiver. Further assessment is needed to understand how these and other factors impact caregiver ratings of a patient’s mood and ability to engage in independent ADL. This study was limited by the restricted range of IADLs questions and the fact that our measure of IADLs was rated by the patient’s caregiver and not based specifically on patient performance. Future research could employ performancebased measures of IADLs to improve validity. Although all of the patients recruited were free of significant neurological or motor impairment, we did not have specific information regarding a patient’s potential physical disabilities such as arthritis that could impact IADL performance. Future research will also need to include ratings of physical disability in order to rule out the potential influence of physical limitations on performance of IADLs. Further, the exclusion of participants who experienced high levels of depression likely restricted our range of depressive symptomology but highlights that, even in a population with relatively low levels of depressive symptoms, patient self-reports are influential in predicting the patient’s ability to complete complex IADLs. Finally, available data
did not allow us to fully clarify the relationship between the caregiver and the patient. Although all caregivers rated their contact with the patient as ‘‘regular,’’ it is possible that the relationships in our study population varied and some caregivers were more knowledgeable than others about the current status of the patients in this sample. Further investigation of this relationship, including comparison of significant other and child ratings, may be valuable in future studies. Acknowledgments The authors thank Michelle McFadden and Tarin Coulas for their assistance in the completion of this study.
Authors’ Note Results of this study were presented at the annual meeting of the International Neuropsychological Society, February 13, 2008, Atlanta, Georgia.
Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was supported by NIH-NIA P50 AG08671 and the Michigan Alzheimer’s Disease Research Center. We would like to acknowledge the National Institute on Aging Claude Pepper Older Adults Independence Center Grant AG08808.
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