ORIGINAL ARTICLE
Quality of Life in Alzheimer Disease A Comparison of Patients’ and Caregivers’ Points of View Chiara Zucchella, PsyD,*w Michelangelo Bartolo, MD, PhD,z Sara Bernini, PsyD,* Marta Picascia, PsyD,* and Elena Sinforiani, MD*
Abstract: Unlike in other chronic diseases, the Quality of Life (QoL) of patients affected by Alzheimer Disease (AD) has not been well established, primarily because of the difficulties stemming from the study of patients with cognitive disorders. Because no cure is currently available for AD, the optimization of QoL represents the best possible outcome attainable in all stages of disease, making QoL assessment mandatory. This study identified variables related to patients’ QoL and examined the agreement between patients’ and caregivers’ QoL ratings. A total of 135 dyads (patient and principal caregiver) were enrolled in the study. Patients’ QoL evaluations showed a negative relationship with depressive mood and a positive relationship with Activities of Daily Living (ADL), whereas caregivers’ QoL ratings showed a negative relationship with patients’ depressive mood and behavioral disturbances. Caregivers tended to underestimate patients’ QoL compared with the patients’ own self-evaluations, with patients’ dependency in performing ADL and behavioral disorders as well as caregivers’ burdens and depression being the main factors associated with the discrepancy in these evaluations. These findings suggest that the use of proxies as a substitute for the self-report of QoL data should be treated with caution, always accounting for the presence of potential bias. Key Words: Alzheimer disease, quality of life, ICF, caregivers, proxies
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he adoption of Quality of Life (QoL) as an outcome measure and the related development of QoL assessment tools have expanded the importance of QoL as an indicator of the benefit of medical interventions in the elderly population.1 Although it is difficult to define such a complex concept, in accordance with the biopsychosocial model of the International Classification of Functioning, Disability and Health (ICF),2 there is general agreement that QoL constitutes a multidimensional construct involving physical and psychological health as well as social relationships and functional status, with a strong component of subjectivity.3
Received for publication March 17, 2014; accepted May 15, 2014. From the *Laboratory of Neuropsychology/Alzheimer Assessment Unit, IRCCS Neurological National Institute C. Mondino Foundation; wDepartment of Public Health, Neuroscience, Experimental and Forensic Medicine, University of Pavia, Pavia; and zNeurorehabilitation Unit, IRCCS NEUROMED, Pozzilli (Isernia), Italy. The authors declare no conflicts of interest. Reprints: Chiara Zucchella, PsyD, Laboratory of Neuropsychology/ Alzheimer Assessment Unit, IRCCS Neurological National Institute C. Mondino Foundation, via Mondino 2, 27100 Pavia, Italy (e-mail: [email protected]). Copyright r 2014 Wolters Kluwer Health, Inc. All rights reserved.
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Among neurodegenerative disorders, Alzheimer disease (AD) is characterized by progressive cognitive and functional impairments that are frequently associated with behavioral and psychological symptoms and can have a profoundly negative impact on patients’ and caregivers’ QoL.4,5 The natural, dynamic, and nonlinear history of dementia and the different therapeutic approaches used in the different evolutionary stages of the disease make QoL assessments for demented patients necessary to provide them with steady improvements in their quality of care.3 In fact, the optimization of QoL by minimizing the associated symptoms represents a positive outcome that is attainable at all stages of disease, and this symptom optimization may involve the use of both pharmacological and nonpharmacological interventions.6 However, because of difficulties in performing such evaluations in subjects with cognitive disorders, QoL investigations in AD patients have not been well established, unlike in other chronic diseases, and no agreed-upon procedure exists for its assessment. Some dated research used proxies as substitutes when patient reports were unavailable,7,8 although the data provided by proxies seem to be affected by systematic bias, which induces caregivers to report lower levels of QoL than patients do,9,10 in line with proxy reporting from other disease areas.11,12 However, little research has been conducted to identify caregiver characteristics that could influence the agreement between patients and caregivers.13 Other than the type of caregiver, the perspective used,12 and the caregiver burden,14 no caregiver characteristics have been identified to date. Moreover, to respect the subjective nature of QoL, it is widely accepted that patients should be the primary source of information regarding their own QoL, and there is evidence that people with dementia can contribute meaningfully to this issue.3,15 Therefore, the aims of the present study were to investigate the mutual relationships among cognitive impairment, mood, behavioral symptoms, functional abilities, and QoL as evaluated by AD patients and their proxies and to examine the level of agreement between patients’ and caregivers’ QoL ratings, identifying factors that might be responsible for any discrepancy.
MATERIALS AND METHODS Participants The study enrolled all consecutive pairs of AD outpatients and their primary caregivers referred to the Alzheimer’s Disease Assessment Unit at our Institution between January 2012 and August 2013. AD was diagnosed in accordance with the NINCDS-ADRDA criteria.16 Patients could be taking cholinesterase inhibitors or
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memantine; patients who were enrolled in clinical trials were excluded. The caregivers had to be informal, such as a family member/partner, and they had to self-define as the primary caregiver of the patient. A primary caregiver was defined as any person who, without being a professional or belonging to a social support network, typically lived with the patient and was either directly implicated in the patient’s care or directly affected by the patient’s health problem.17 The patients and caregivers were enrolled after clinicians (E.S., C.Z.) had fully explained the study to them after they had given their written informed consent to participate. The study had local ethics committee approval and was conducted in accordance with the revised version of the Helsinki Declaration.
Measures Sociodemographic and lifestyle information (sex, age, education, work, family situation, living arrangement) were collected from patients and caregivers. To assess global cognitive functioning and mood, an expert neuropsychologist evaluated all of the patients using the following measures: Mini Mental State Examination (MMSE)18: Scores range from 0 to 30, with lower scores corresponding to higher cognitive impairment; Geriatric Depression Scale (GDS)19: Higher scores correspond to more severe emotional disturbances. To collect information about patients’ independence and behavioral disturbances, the caregivers were interviewed by the same neuropsychologist using the following scales: Activity of Daily Living (ADL)20: Evaluates a patient’s ability to perform basic daily activities; scores range from 0 to 6, with higher scores corresponding to higher levels of autonomy; Instrumental Activity of Daily Living (IADL)21: Evaluates a patient’s ability to perform instrumental activities; scores range from 0 to 8, with higher scores corresponding to higher levels of autonomy; Neuropsychiatric Inventory (NPI)22: Investigates the presence and severity of behavioral disorders; scores range from 0 to 144, with higher scores corresponding to more severe behavioral disorders. All the caregivers were instructed to complete the following questionnaires: Beck Depression Inventory (BDI)23: Assesses the mood; higher scores correspond to more severe emotional disturbances; Caregiver Burden Inventory (CBI)24: Assesses the burden of care as perceived by caregivers of AD patients; higher scores (range, 0 to 96) indicate greater levels of perceived burden. To assess the patients’ QoL, all patients and their proxies completed the Quality of Life-AD (QoL-AD) instrument.15 The QoL-AD is a self-evaluation comprising 13 items that cover the following domains: physical health; energy; mood; living situation; memory; family; marriage; friends; chores; fun; money; self; and life as a whole. Answers are rated on a 4-point Likert scale: 1 (poor), 2 (fair), 3 (good), and 4 (excellent). The questionnaire was administered to patients in an interview format, whereas caregivers completed the questionnaire about the patient on their own. Caregivers were instructed to “Please rate your relative’s current situation, as you see it.” Copyright
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The QoL-AD thus provides 2 scores that represent the sum of the 13 items, namely QoL as scored by the patient and patients’ QoL as scored by the caregiver. The total QoL-AD score ranged from 13 (worst QoL) to 52 (highest QoL). A composite score was created using both sources of information but prioritizing the patient’s evaluation (the patient’s total score was multiplied by 2 before being added to the caregiver’s total score, and the sum was then divided by 3). In this study, for our purposes, this last score was neither computed nor utilized in the statistical analysis. This measure was selected because there is evidence for the validity and reliability of the QOL-AD in people with MMSE scores ranging between 3 and 11, and the measure is practical for use and administration in this population.25 All of the patients and their proxies were individually evaluated or interviewed by the same expert neuropsychologist; they completed the questionnaires separately.
Statistical Analysis Quantitative variables were described as the means ± SD and qualitative data as number and percentage. To clarify the mutual relationships among cognitive impairment, mood, behavioral symptoms, functional abilities, and QoL, correlational analyses (Pearson’s r) were carried out. For each item and for the overall QoL-AD score, the average of the patients’ scores and the average of the caregivers’ scores were compared using Student t test. To detect factors that were significantly associated with the difference between the patients’ QoL total score and their caregivers’ QoL total score, a generalized linear regression was performed, considering the difference to be the quantitative dependent variable. The differences were calculated such that a positive difference indicated that the caregiver rated the patient’s QoL lower than the patient did (patient score caregiver score). The independent variables were patients’ disease duration, caregivers’ characteristics (retirement, cohabitation), and the values of the clinical scales (MMSE, GDS, NPI, ADL/IADL, BDI, and CBI). For all analyses, the level of statistical significance was set at Pr0.05. Statistical analysis was performed using the Statistical Package for the Social Sciences, version 17.0 for Windows (version 17.0. SPSS Inc., Chicago, IL).
RESULTS Of the 141 consecutive dyads referred to the study, 135 met the eligibility criteria. A total of 6 dyads were excluded because the caregivers were not informal (2), the patients were institutionalized (2), or the caregivers did not consent to participate in the study (2). Table 1 shows the sociodemographic and clinical characteristics of the study population. The Pearson product-moment correlation coefficient revealed that QoL (evaluated by the patients) showed a negative relationship with depressive mood (GDS) (r = 0.563, P = 0.000) and a positive relationship with ADL (r = 0.238, P = 0.006). QoL (evaluated by the caregivers) showed a negative relationship with depressive mood (GDS) (r = 0.347, P = 0.000) and with behavioral disturbances (NPI) (r = 232, P = 0.007). The comparisons of total QoL-AD scores between patients (32.1 ± 7.3) and caregivers (26.9 ± 7.2) revealed a statistically significant difference (P = 0.000), with the
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TABLE 1. Sociodemographic and Clinical Features
Patients (n = 135)
Features Sociodemographic features Age (y) Education (y) Sex (F/M) 93 Relationship with the patient Daughter/son Spouse/cohabitant Nephews Daughter in law/son in law Friends Sister Cousin Living with the patient Retired/housewives Clinical features Disease duration (y) Cholinesterase Inhibitors Memantine MMSE ADL IADL NPI GDS BDI CBI
78.2 ± 5.9 5.8 ± 2.7 (68.9)/42 (31.1)
59.7 ± 13.2 10.6 ± 4.3 85 (63)/50 (37) (52.6) (36.3) (5.2) (2.2)
2 2 1 76 72
(1.5) (1.5) (0.7) (56.3) (53.3)
QoL-Items
Patients Caregivers
Physical health Energy Mood Living situation Memory Family Marriage Friends Self as a whole Ability to do chores around the house Ability to do things for fun Money Life as a whole QoL total score
2.6 ± 0.8 2.5 ± 0.9 2.6 ± 0.8 3.2 ± 0.8 1.9 ± 0.7 3.0 ± 0.9 2.5 ± 1.3 2.4 ± 1.0 2.5 ± 0.7 2.3 ± 0.9
P
2.3 ± 0.8 2.0 ± 0.8 2.0 ± 0.8 2.7 ± 0.8 1.6 ± 0.8 2.6 ± 0.8 2.3 ± 1.0 2.0 ± 0.9 2.1 ± 0.8 1.9 ± 1.0
0.00 0.00 0.00 0.00 0.00 0.00 NS 0.00 0.00 0.00
1.8 ± 0.9 1.6 ± 0.8 2.5 ± 0.7 2.2 ± 0.8 2.5 ± 0.8 2.2 ± 0.7 32.1 ± 7.3 26.9 ± 7.2
0.05 0.00 0.00 0.00
Data are expressed as mean ± SD. Significance: Pr0.05. NS indicates not significant; QOL, Quality of Life.
4.1 ± 2.4 112 (83) 23 (17) 15.3 ± 7.5 4.6 ± 1.5 3.2 ± 2.4 4.6 ± 6.7 9.3 ± 6.0 8.3 ± 7.0 24.8 ± 16.3
Data are expressed as mean ± SD or number (%). ADL indicates Activity of Daily Living; BDI, Beck Depression Inventory; CBI, Caregiver Burden Inventory; GDS, Geriatric Depression Scale; IADL, Instrumental Activity of Daily Living; MMSE, Mini Mental State Examination; NPI, Neuropsychiatric Inventory.
caregivers’ evaluations being consistently lower. An analysis of the specific items from the questionnaire confirmed that caregivers significantly underestimated item ratings compared with the patients’ self-evaluations, with the exception of the item “marriage,” which was the only one that did not significantly differ between the 2 groups. The data are summarized in Table 2. The same analysis was repeated in the subgroup of 61 pairs of patients (39F/22M, mean age 77.5 ± 5.9 y, GDS 5.1 ± 2.2 mean score) and caregivers (33F/28M, mean age 61.6 ± 12.8, BDI 4.7 ± 3.6 mean score) who did not show depressive symptoms. This comparison revealed that even in this population, both the total QoL-AD score and the scores of most of the items were significantly higher in the patients’ self-evaluation; only the scores for items regarding marriage, friends, and fun were not significantly different between the groups. The regression analysis revealed that the main factors associated with the degree of difference between patients and their caregivers were as follows: the presence of depressive disorder suffered by the patient (GDS), the level of patient’s dependency in performing basic activities of daily living (ADL), the presence of psychological and behavioral disorders (NPI), the perception of the burden experienced by caregivers related to assistance (CBI), and caregivers’ depression (BDI) (Table 3).
DISCUSSION The results of this study showed that patients’ QoL self-evaluations were associated with their mood and their
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TABLE 2. QoL Evaluations: Comparison Between Patients and Caregivers
Caregivers (n = 135)
71 49 7 3
ability to perform basic ADL, whereas patients’ QoL as evaluated by their caregivers was associated with mood and behavioral disturbances. The overlap is obvious and predictable and replicates a clear and consistent pattern that can be observed for depression with both self-reports and proxy-reports of health-related QoL in mild to moderate dementia, suggesting that more severe depression indicates a lower QoL.26–28 In addition to mood, the caregivers’ reports suggested an inverse relationship between neuropsychiatric symptoms and patient’s QoL. Considering the strong link between behavioral disturbances and caregivers’ burden,29 it has been suggested that caregivers may use a mechanism of “projection” that leads them to “project” part of their own QoL problems onto patients’ QoL.13 In other words, caregivers might underestimate the QoL of patients if they experience a diminished QoL themselves. Moreover, according to our data, at least for AD patients, the dependency levels seems to greatly influence their own perceptions of QoL and, when viewed as a global measure, most likely reflect a certain level of QoL, which could be
TABLE 3. Regression Analysis
Variables MMSE GDS Disease duration ADL IADL NPI CBI BDI Retirement Cohabitation
b
t
P
0.063 0.244 0.092 0.336 0.203 0.161 0.279 0.188 0.007 0.016
0.704 2.932 1.109 3.353 1.765 1.960 2.495 1.998 0.068 0.167
0.48 0.00* 0.27 0.00* 0.08 0.05* 0.01* 0.04* 0.94 0.86
Regression summary for Dependent Variable-Difference QoLPtQoLCG: R2 = 0.295; F5,61; P < 0.000. *Significance Pr0.05. ADL indicates Activity of Daily Living; BDI, Beck Depression Inventory; CBI, Caregiver Burden Inventory; GDS, Geriatric Depression Scale; IADL, Instrumental Activity of Daily Living; MMSE, Mini Mental State Examination; NPI, Neuropsychiatric Inventory.
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considered an indirect measure.30 However, in the literature, the relationship between activity limitations and QoL has not always been replicated in patients’ self-ratings,31,32 and conflicting evidence exists as to whether independence in basic activities can be considered as a key-feature of QoL. Patients’ age, cognition, and duration of disease do not seem to be major determinants of QoL in our study, as has already been reported in previous papers.28,33 When considering the degree of agreement between patients and caregivers, our findings indicated that caregivers significantly underestimated QoL compared with the patients’ self-evaluations, a finding that is consistent with the extant literature.9,10 Interestingly, the analysis suggested that this discrepancy is not evident in specific areas but instead reflects an overall attitude of underestimation from the caregivers across all domains. This difference is also confirmed in the subgroup of nondepressed subjects (patients and caregivers), indicating that although mood is an important factor, it cannot alone explain this variance, which is likely to be attributed to a set of variables. These observations could be conceptualized in the context of the “disability paradox,” which refers to the fact that many people with serious and persistent disabilities report that they experience a good QoL when, to most external observers, these individuals seem to live an undesirable daily existence.34 According to other authors, the explanation for this paradox should be sought in the complex balance among body, mind, and spirit upon which QoL depends and which presents a strong subjective nature. Clearly, self-perceived QoL depends on a variety of factors, including familial, financial, individual, interpersonal, marital, professional, physical, spiritual, and social attributes. Any of these may affect an individual’s selfperceived QoL, and from any of these can an individual derive elements of resilience that are not always available for others to cope with the disease and progressively adapt. A lack of awareness about the disease in the patients could represent another possible explanation, possibly a simpler one, for their tendency to overestimate their own QoL with respect to proxies. However, in our sample, the patients showed only a moderate degree of dementia (MMSE on average 15.3 ± 7.5), not a severe degree, and it can therefore be assumed that awareness was at least partially preserved. Moreover, some evidence suggests that degree of insight is unconnected with QoL in early dementia, when insight is maintained.10 The correct approach would likely be to consider these 2 interpretations to be complementary, not mutually exclusive. Concerning the specific variables that seem to account for the primary differences in patients’ and caregivers’ evaluations, results from the regression analysis identified factors related to both patients and caregivers. Patients’ mood disturbances seem to reduce the discrepancy, likely because depressed patients rate their own QoL lower and therefore closer to their caregivers’ evaluations; conversely, independence in performing basic ADL seems to increase the difference. It is possible that being independent in basic activities induces patients to judge their QoL higher than do their caregivers, for whom this aspect could not be as relevant. This independence in basic activities such as bathing, dressing, and feeding relates to a very “intimate” sphere of the individual, which has high value for patients and is perhaps not entirely understood by caregivers, who focus more on instrumental complex tasks. Other factors that appear to be predictive of a greater discrepancy between patients and proxies are the presence Copyright
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of patients’ neuropsychiatric symptoms and caregivers’ depression and perceived burden. Consistent with our data, extensive evidence exists that an increasing behavioral disorder is associated with decreased QoL for caregiver ratings, but the pattern is not repeated for self-reports. This may reflect a decreased patient insight associated with dementia or a differential appraisal of the impacts of emerging behavioral disorder in people with dementia compared with proxies.35 Behavioral and psychological symptoms, in turn, are routinely cited as important predictors of caregiver burden and depression that, according to the literature, are strongly related36,37 and are known to induce caregivers to underestimate the QoL of their relatives.38 Conversely, caregivers’ living arrangements and work status did not seem to be major determinants of QoL in our study, which may indicate that the differences in the ratings between patients and caregivers depend more on psychological/affective variables and coping strategies39 than on objective aspects. The participants in this study presented with moderate cognitive impairment and lived at their home; it is unclear whether these results can be generalizable to people with severe AD or those living in residential care facilities. This sample selectivity could represent an experimental limitation and should be verified in future studies. In conclusion, the results of this study showed that patients and their family members do not always agree in their evaluations of patient’s QoL, so the use of proxies as a substitute when self-reports of QoL data are unavailable should be considered with caution, always considering the presence of potential bias. Despite these difficulties, focusing on the subjective aspects of QoL in chronic neurodegenerative diseases such as dementia is of utmost importance because health care professionals may have a greater chance of intervention into this issue than into other aspects of the disease. Therefore, there is a pressing need for studies in large, representative samples of people with dementia that are both cross-sectional and longitudinal in design to clarify the natural history of QoL in dementia and identify an intervention that can promote it.
REFERENCES 1. Whitehouse PJ, Patterson MB, Sami SA. Quality of life in dementia: ten years later. Alzheimer Dis Assoc Disord. 2003;17:199–200. 2. World Health Organization. International Classification of Functioning, Disability and Health (ICF). Geneva, Switzerland: WHO; 2001. 3. Smith SC, Murray J, Banerjee S, et al. What constitutes healthrelated quality of life in dementia? Development of a conceptual framework for people with dementia and their carers. Int J Geriatr Psychiatry. 2005;20:889–895. 4. Shin IS, Carter M, Masterman D, et al. Neuropsychiatric symptoms and quality of life in Alzheimer’s disease. Am J Geriatr Psychiatry. 2005;13:469–474. 5. Jonsson L, Andreasen N, Kilander L, et al. Patient- and proxyreported utility in Alzheimer’s disease using the EuroQoL. Alzheimer Dis Assoc Disord. 2006;20:49e55. 6. Zhao H, Novella JL, Drame` M, et al. Factors associated with caregivers’ underestimation of quality of life in patients with Alzheimer’s disease. Dement Geriatr Cogn Disord. 2012; 33:11–17. 7. Nelson LM, Longstreth WTJ, Koepsell TD, et al. Proxy respondents in epidemiologic research. Epidemiol Rev. 1990; 12:71–86.
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8. Seckler AB, Meier DE, Mulvihill M, et al. Substituted judgment: how accurate are proxy predictions? Ann Intern Med. 1991;115:92–98. 9. Ready RE, Ott B, Grace J. Patient versus informant perspectives of quality of life in mild cognitive impairment and Alzheimer’s disease. Int J Geriatr Psychiatry. 2004;19: 256–265. 10. Vogel A, Mortensen EL, Hasselbalch SG, et al. Patient versus informant reported quality of life in the earliest phases of Alzheimer’s disease. Int J Geriatr Psychiatry. 2006;21: 1132–1138. 11. Sneeuw KCA, Sprangers MAG, Aaronson NK. The role of health care providers and significant others in evaluating the quality of life of patients with chronic disease. J Clin Epidemiol. 2002;55:1130–1143. 12. McPhail S, Beller E, Haines T. Two perspectives of proxy reporting of health-related quality of life using the euroqol-5D, an investigation of agreement. Med Care. 2008;46:1140–1148. 13. Arons AM, Krabbe PF, Scho¨lzel-Dorenbos CJ, et al. Quality of life in dementia: a study on proxy bias. BMC Med Res Methodol. 2013;13:110. 14. Sands LP, Ferreira P, Stewart AL, et al. What explains differences between dementia patients’ and their caregivers’ ratings of patients’ quality of life? Am J Geriat Psychiat. 2004;12:272–280. 15. Logsdon RG, Gibbons LE, McCurry SM, et al. Quality of life in Alzheimer’s disease: patient and caregiver reports. J Mental Health Aging. 1999;5:21–32. 16. Mckhann G, Drachman D, Folstein M, et al. Clinical diagnosis of Alzheimer’s disease: report of the NINCDS-ADRDA Work Group under the auspices of Department of Health and Human Services Task Force on Alzheimer’s Disease. Neurology. 1984;34:939–944. 17. Martinez-Martin P, Forjaz MJ, Frades-Payo B, et al. Caregiver burden in Parkinson’s disease. Mov Disord. 2007;22: 924–931. 18. Folstein MF, Folstein SE, McHugh PR. Mini Mental State. J Psychiatr Res. 1975;12:189–198. 19. Yesavage JA, Brink TL, Rose TL, et al. Development and validation of a geriatric depression screening scale: a preliminary report. J Psychiatr Res. 1982-83;17:37–49. 20. Lawton MP. Scales to measure competence in everyday activities. Psychopharmacol Bull. 1988;24:609–614. 21. Lawton MP, Brody EM. Assessment of older people: selfmaintaining and instrumental activities of daily living. Gerontology. 1969;9:179–186. 22. Cummings JL, Mega M, Gray K, et al. The Neuropsychiatric Inventory: comprehensive assessment of psychopathology in dementia. Neurology. 1994;44:2308–2314. 23. Beck AT, Ward CH, Mendelson M, et al. An Inventory for measuring depression. Arch Gen Psychiatr. 1961;4:561–571. 24. Novak M, Guest C. Application of a multidimensional caregiver burden inventory. Gerontologist. 1989;29:798–803.
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25. Hoe J, Katona C, Roch B, et al. Use of the QOL-AD for measuring quality of life in people with severe dementia—the LASER-AD study. Age Aging. 2005;34:130–135. 26. Conde-Sala JL, Garre-Olmo J, Turro´-Garriga O, et al. Factors related to perceived quality of life in patients with Alzheimer’s disease: the patient’s perception compared with that of caregivers. Int J Geriatr Psychiatry. 2009;24:585–594. 27. Go´mez-Gallego M, Go´mez-Amor J, Go´mez-Garcı´ a J. Determinants of quality of life in Alzheimer’s disease: perspective of patients, informal caregivers, and professional caregivers. Int Psychogeriatr. 2012;24:1805–1815. 28. Leo´n-Salas B, Olazara´n J, Cruz-Ordun˜a I, et al. Quality of life (QoL) in community-dwelling and institutionalized Alzheimer’s disease (AD) patients. Arch Gerontol Geriatr. 2013; 57:257–262. 29. Matsumoto N, Ikeda M, Fukuhara R, et al. Caregiver burden associated with behavioral and psychological symptoms of dementia in elderly people in the local community. Dement Geriatr Cogn Disord. 2007;23:219–224. 30. Andersen CK, Wittrup-Jensen KU, Lolk A, et al. Ability to perform activities of daily living is the main factor affecting quality of life in patients with dementia. Health Qual Life Outcomes. 2004;2:52. 31. Edelman P, Fulton BR, Kuhn D, et al. A comparison of three methods of measuring dementia-specific quality of life: perspectives of residents, staff, and observers. Gerontologist. 2005;45:27–36. 32. Fuh J, Wang S. Assessing quality of life in Taiwanese patients with Alzheimer’s disease. Int J Geriatr Psychiatry. 2006; 21:103–107. 33. Thomas P, Lalloue F, Preux PM, et al. Dementia patients caregivers quality of life: the PIXEL study. Int J Geriatr Psychiatry. 2006;21:50–56. 34. Albrecht GL, Devlieger PJ. The disability paradox: high quality of life against all odds. Soc Sci Med. 1999;48:977–988. 35. Banerjee S, Samsi K, Petrie CD, et al. What do we know about quality of life in dementia? A review of the emerging evidence on the predictive and explanatory value of disease specific measures of health related quality of life in people with dementia. Int J Geriatr Psychiatry. 2009;24:15–24. 36. Bartolo M, De Luca D, Serrao M, et al. Caregiver burden and needs in community neurorehabilitation. J Rehabil Med. 2010;42:818–822. 37. D’Aoust RF, Brewster G, Rowe MA. Depression in informal caregivers of persons with dementia. Int J Older People Nurs. 2014. doi: 10.1111/opn.12043. [Epub ahead of print]. 38. Conde-Sala JL, Ren˜e´-Ramı´ rez R, Turro´-Garriga O, et al. Factors associated with the variability in caregiver assessments of the capacities of patients with Alzheimer disease. J Geriatr Psychiatry Neurol. 2013;26:86–94. 39. Zucchella C, Bartolo M, Pasotti C, et al. Caregiver burden and coping in early-stage Alzheimer disease. Alzheimer Dis Assoc Disord. 2012;26:55–60.
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Quality of Life in Alzheimer Disease A Comparison of Patients’ and Caregivers’ Points of View Chiara Zucchella, PsyD,*w Michelangelo Bartolo, MD, PhD,z Sara Bernini, PsyD,* Marta Picascia, PsyD,* and Elena Sinforiani, MD*
Abstract: Unlike in other chronic diseases, the Quality of Life (QoL) of patients affected by Alzheimer Disease (AD) has not been well established, primarily because of the difficulties stemming from the study of patients with cognitive disorders. Because no cure is currently available for AD, the optimization of QoL represents the best possible outcome attainable in all stages of disease, making QoL assessment mandatory. This study identified variables related to patients’ QoL and examined the agreement between patients’ and caregivers’ QoL ratings. A total of 135 dyads (patient and principal caregiver) were enrolled in the study. Patients’ QoL evaluations showed a negative relationship with depressive mood and a positive relationship with Activities of Daily Living (ADL), whereas caregivers’ QoL ratings showed a negative relationship with patients’ depressive mood and behavioral disturbances. Caregivers tended to underestimate patients’ QoL compared with the patients’ own self-evaluations, with patients’ dependency in performing ADL and behavioral disorders as well as caregivers’ burdens and depression being the main factors associated with the discrepancy in these evaluations. These findings suggest that the use of proxies as a substitute for the self-report of QoL data should be treated with caution, always accounting for the presence of potential bias. Key Words: Alzheimer disease, quality of life, ICF, caregivers, proxies
(Alzheimer Dis Assoc Disord 2015;29:50–54)
T
he adoption of Quality of Life (QoL) as an outcome measure and the related development of QoL assessment tools have expanded the importance of QoL as an indicator of the benefit of medical interventions in the elderly population.1 Although it is difficult to define such a complex concept, in accordance with the biopsychosocial model of the International Classification of Functioning, Disability and Health (ICF),2 there is general agreement that QoL constitutes a multidimensional construct involving physical and psychological health as well as social relationships and functional status, with a strong component of subjectivity.3
Received for publication March 17, 2014; accepted May 15, 2014. From the *Laboratory of Neuropsychology/Alzheimer Assessment Unit, IRCCS Neurological National Institute C. Mondino Foundation; wDepartment of Public Health, Neuroscience, Experimental and Forensic Medicine, University of Pavia, Pavia; and zNeurorehabilitation Unit, IRCCS NEUROMED, Pozzilli (Isernia), Italy. The authors declare no conflicts of interest. Reprints: Chiara Zucchella, PsyD, Laboratory of Neuropsychology/ Alzheimer Assessment Unit, IRCCS Neurological National Institute C. Mondino Foundation, via Mondino 2, 27100 Pavia, Italy (e-mail: [email protected]). Copyright r 2014 Wolters Kluwer Health, Inc. All rights reserved.
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Among neurodegenerative disorders, Alzheimer disease (AD) is characterized by progressive cognitive and functional impairments that are frequently associated with behavioral and psychological symptoms and can have a profoundly negative impact on patients’ and caregivers’ QoL.4,5 The natural, dynamic, and nonlinear history of dementia and the different therapeutic approaches used in the different evolutionary stages of the disease make QoL assessments for demented patients necessary to provide them with steady improvements in their quality of care.3 In fact, the optimization of QoL by minimizing the associated symptoms represents a positive outcome that is attainable at all stages of disease, and this symptom optimization may involve the use of both pharmacological and nonpharmacological interventions.6 However, because of difficulties in performing such evaluations in subjects with cognitive disorders, QoL investigations in AD patients have not been well established, unlike in other chronic diseases, and no agreed-upon procedure exists for its assessment. Some dated research used proxies as substitutes when patient reports were unavailable,7,8 although the data provided by proxies seem to be affected by systematic bias, which induces caregivers to report lower levels of QoL than patients do,9,10 in line with proxy reporting from other disease areas.11,12 However, little research has been conducted to identify caregiver characteristics that could influence the agreement between patients and caregivers.13 Other than the type of caregiver, the perspective used,12 and the caregiver burden,14 no caregiver characteristics have been identified to date. Moreover, to respect the subjective nature of QoL, it is widely accepted that patients should be the primary source of information regarding their own QoL, and there is evidence that people with dementia can contribute meaningfully to this issue.3,15 Therefore, the aims of the present study were to investigate the mutual relationships among cognitive impairment, mood, behavioral symptoms, functional abilities, and QoL as evaluated by AD patients and their proxies and to examine the level of agreement between patients’ and caregivers’ QoL ratings, identifying factors that might be responsible for any discrepancy.
MATERIALS AND METHODS Participants The study enrolled all consecutive pairs of AD outpatients and their primary caregivers referred to the Alzheimer’s Disease Assessment Unit at our Institution between January 2012 and August 2013. AD was diagnosed in accordance with the NINCDS-ADRDA criteria.16 Patients could be taking cholinesterase inhibitors or
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memantine; patients who were enrolled in clinical trials were excluded. The caregivers had to be informal, such as a family member/partner, and they had to self-define as the primary caregiver of the patient. A primary caregiver was defined as any person who, without being a professional or belonging to a social support network, typically lived with the patient and was either directly implicated in the patient’s care or directly affected by the patient’s health problem.17 The patients and caregivers were enrolled after clinicians (E.S., C.Z.) had fully explained the study to them after they had given their written informed consent to participate. The study had local ethics committee approval and was conducted in accordance with the revised version of the Helsinki Declaration.
Measures Sociodemographic and lifestyle information (sex, age, education, work, family situation, living arrangement) were collected from patients and caregivers. To assess global cognitive functioning and mood, an expert neuropsychologist evaluated all of the patients using the following measures: Mini Mental State Examination (MMSE)18: Scores range from 0 to 30, with lower scores corresponding to higher cognitive impairment; Geriatric Depression Scale (GDS)19: Higher scores correspond to more severe emotional disturbances. To collect information about patients’ independence and behavioral disturbances, the caregivers were interviewed by the same neuropsychologist using the following scales: Activity of Daily Living (ADL)20: Evaluates a patient’s ability to perform basic daily activities; scores range from 0 to 6, with higher scores corresponding to higher levels of autonomy; Instrumental Activity of Daily Living (IADL)21: Evaluates a patient’s ability to perform instrumental activities; scores range from 0 to 8, with higher scores corresponding to higher levels of autonomy; Neuropsychiatric Inventory (NPI)22: Investigates the presence and severity of behavioral disorders; scores range from 0 to 144, with higher scores corresponding to more severe behavioral disorders. All the caregivers were instructed to complete the following questionnaires: Beck Depression Inventory (BDI)23: Assesses the mood; higher scores correspond to more severe emotional disturbances; Caregiver Burden Inventory (CBI)24: Assesses the burden of care as perceived by caregivers of AD patients; higher scores (range, 0 to 96) indicate greater levels of perceived burden. To assess the patients’ QoL, all patients and their proxies completed the Quality of Life-AD (QoL-AD) instrument.15 The QoL-AD is a self-evaluation comprising 13 items that cover the following domains: physical health; energy; mood; living situation; memory; family; marriage; friends; chores; fun; money; self; and life as a whole. Answers are rated on a 4-point Likert scale: 1 (poor), 2 (fair), 3 (good), and 4 (excellent). The questionnaire was administered to patients in an interview format, whereas caregivers completed the questionnaire about the patient on their own. Caregivers were instructed to “Please rate your relative’s current situation, as you see it.” Copyright
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The QoL-AD thus provides 2 scores that represent the sum of the 13 items, namely QoL as scored by the patient and patients’ QoL as scored by the caregiver. The total QoL-AD score ranged from 13 (worst QoL) to 52 (highest QoL). A composite score was created using both sources of information but prioritizing the patient’s evaluation (the patient’s total score was multiplied by 2 before being added to the caregiver’s total score, and the sum was then divided by 3). In this study, for our purposes, this last score was neither computed nor utilized in the statistical analysis. This measure was selected because there is evidence for the validity and reliability of the QOL-AD in people with MMSE scores ranging between 3 and 11, and the measure is practical for use and administration in this population.25 All of the patients and their proxies were individually evaluated or interviewed by the same expert neuropsychologist; they completed the questionnaires separately.
Statistical Analysis Quantitative variables were described as the means ± SD and qualitative data as number and percentage. To clarify the mutual relationships among cognitive impairment, mood, behavioral symptoms, functional abilities, and QoL, correlational analyses (Pearson’s r) were carried out. For each item and for the overall QoL-AD score, the average of the patients’ scores and the average of the caregivers’ scores were compared using Student t test. To detect factors that were significantly associated with the difference between the patients’ QoL total score and their caregivers’ QoL total score, a generalized linear regression was performed, considering the difference to be the quantitative dependent variable. The differences were calculated such that a positive difference indicated that the caregiver rated the patient’s QoL lower than the patient did (patient score caregiver score). The independent variables were patients’ disease duration, caregivers’ characteristics (retirement, cohabitation), and the values of the clinical scales (MMSE, GDS, NPI, ADL/IADL, BDI, and CBI). For all analyses, the level of statistical significance was set at Pr0.05. Statistical analysis was performed using the Statistical Package for the Social Sciences, version 17.0 for Windows (version 17.0. SPSS Inc., Chicago, IL).
RESULTS Of the 141 consecutive dyads referred to the study, 135 met the eligibility criteria. A total of 6 dyads were excluded because the caregivers were not informal (2), the patients were institutionalized (2), or the caregivers did not consent to participate in the study (2). Table 1 shows the sociodemographic and clinical characteristics of the study population. The Pearson product-moment correlation coefficient revealed that QoL (evaluated by the patients) showed a negative relationship with depressive mood (GDS) (r = 0.563, P = 0.000) and a positive relationship with ADL (r = 0.238, P = 0.006). QoL (evaluated by the caregivers) showed a negative relationship with depressive mood (GDS) (r = 0.347, P = 0.000) and with behavioral disturbances (NPI) (r = 232, P = 0.007). The comparisons of total QoL-AD scores between patients (32.1 ± 7.3) and caregivers (26.9 ± 7.2) revealed a statistically significant difference (P = 0.000), with the
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TABLE 1. Sociodemographic and Clinical Features
Patients (n = 135)
Features Sociodemographic features Age (y) Education (y) Sex (F/M) 93 Relationship with the patient Daughter/son Spouse/cohabitant Nephews Daughter in law/son in law Friends Sister Cousin Living with the patient Retired/housewives Clinical features Disease duration (y) Cholinesterase Inhibitors Memantine MMSE ADL IADL NPI GDS BDI CBI
78.2 ± 5.9 5.8 ± 2.7 (68.9)/42 (31.1)
59.7 ± 13.2 10.6 ± 4.3 85 (63)/50 (37) (52.6) (36.3) (5.2) (2.2)
2 2 1 76 72
(1.5) (1.5) (0.7) (56.3) (53.3)
QoL-Items
Patients Caregivers
Physical health Energy Mood Living situation Memory Family Marriage Friends Self as a whole Ability to do chores around the house Ability to do things for fun Money Life as a whole QoL total score
2.6 ± 0.8 2.5 ± 0.9 2.6 ± 0.8 3.2 ± 0.8 1.9 ± 0.7 3.0 ± 0.9 2.5 ± 1.3 2.4 ± 1.0 2.5 ± 0.7 2.3 ± 0.9
P
2.3 ± 0.8 2.0 ± 0.8 2.0 ± 0.8 2.7 ± 0.8 1.6 ± 0.8 2.6 ± 0.8 2.3 ± 1.0 2.0 ± 0.9 2.1 ± 0.8 1.9 ± 1.0
0.00 0.00 0.00 0.00 0.00 0.00 NS 0.00 0.00 0.00
1.8 ± 0.9 1.6 ± 0.8 2.5 ± 0.7 2.2 ± 0.8 2.5 ± 0.8 2.2 ± 0.7 32.1 ± 7.3 26.9 ± 7.2
0.05 0.00 0.00 0.00
Data are expressed as mean ± SD. Significance: Pr0.05. NS indicates not significant; QOL, Quality of Life.
4.1 ± 2.4 112 (83) 23 (17) 15.3 ± 7.5 4.6 ± 1.5 3.2 ± 2.4 4.6 ± 6.7 9.3 ± 6.0 8.3 ± 7.0 24.8 ± 16.3
Data are expressed as mean ± SD or number (%). ADL indicates Activity of Daily Living; BDI, Beck Depression Inventory; CBI, Caregiver Burden Inventory; GDS, Geriatric Depression Scale; IADL, Instrumental Activity of Daily Living; MMSE, Mini Mental State Examination; NPI, Neuropsychiatric Inventory.
caregivers’ evaluations being consistently lower. An analysis of the specific items from the questionnaire confirmed that caregivers significantly underestimated item ratings compared with the patients’ self-evaluations, with the exception of the item “marriage,” which was the only one that did not significantly differ between the 2 groups. The data are summarized in Table 2. The same analysis was repeated in the subgroup of 61 pairs of patients (39F/22M, mean age 77.5 ± 5.9 y, GDS 5.1 ± 2.2 mean score) and caregivers (33F/28M, mean age 61.6 ± 12.8, BDI 4.7 ± 3.6 mean score) who did not show depressive symptoms. This comparison revealed that even in this population, both the total QoL-AD score and the scores of most of the items were significantly higher in the patients’ self-evaluation; only the scores for items regarding marriage, friends, and fun were not significantly different between the groups. The regression analysis revealed that the main factors associated with the degree of difference between patients and their caregivers were as follows: the presence of depressive disorder suffered by the patient (GDS), the level of patient’s dependency in performing basic activities of daily living (ADL), the presence of psychological and behavioral disorders (NPI), the perception of the burden experienced by caregivers related to assistance (CBI), and caregivers’ depression (BDI) (Table 3).
DISCUSSION The results of this study showed that patients’ QoL self-evaluations were associated with their mood and their
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TABLE 2. QoL Evaluations: Comparison Between Patients and Caregivers
Caregivers (n = 135)
71 49 7 3
ability to perform basic ADL, whereas patients’ QoL as evaluated by their caregivers was associated with mood and behavioral disturbances. The overlap is obvious and predictable and replicates a clear and consistent pattern that can be observed for depression with both self-reports and proxy-reports of health-related QoL in mild to moderate dementia, suggesting that more severe depression indicates a lower QoL.26–28 In addition to mood, the caregivers’ reports suggested an inverse relationship between neuropsychiatric symptoms and patient’s QoL. Considering the strong link between behavioral disturbances and caregivers’ burden,29 it has been suggested that caregivers may use a mechanism of “projection” that leads them to “project” part of their own QoL problems onto patients’ QoL.13 In other words, caregivers might underestimate the QoL of patients if they experience a diminished QoL themselves. Moreover, according to our data, at least for AD patients, the dependency levels seems to greatly influence their own perceptions of QoL and, when viewed as a global measure, most likely reflect a certain level of QoL, which could be
TABLE 3. Regression Analysis
Variables MMSE GDS Disease duration ADL IADL NPI CBI BDI Retirement Cohabitation
b
t
P
0.063 0.244 0.092 0.336 0.203 0.161 0.279 0.188 0.007 0.016
0.704 2.932 1.109 3.353 1.765 1.960 2.495 1.998 0.068 0.167
0.48 0.00* 0.27 0.00* 0.08 0.05* 0.01* 0.04* 0.94 0.86
Regression summary for Dependent Variable-Difference QoLPtQoLCG: R2 = 0.295; F5,61; P < 0.000. *Significance Pr0.05. ADL indicates Activity of Daily Living; BDI, Beck Depression Inventory; CBI, Caregiver Burden Inventory; GDS, Geriatric Depression Scale; IADL, Instrumental Activity of Daily Living; MMSE, Mini Mental State Examination; NPI, Neuropsychiatric Inventory.
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considered an indirect measure.30 However, in the literature, the relationship between activity limitations and QoL has not always been replicated in patients’ self-ratings,31,32 and conflicting evidence exists as to whether independence in basic activities can be considered as a key-feature of QoL. Patients’ age, cognition, and duration of disease do not seem to be major determinants of QoL in our study, as has already been reported in previous papers.28,33 When considering the degree of agreement between patients and caregivers, our findings indicated that caregivers significantly underestimated QoL compared with the patients’ self-evaluations, a finding that is consistent with the extant literature.9,10 Interestingly, the analysis suggested that this discrepancy is not evident in specific areas but instead reflects an overall attitude of underestimation from the caregivers across all domains. This difference is also confirmed in the subgroup of nondepressed subjects (patients and caregivers), indicating that although mood is an important factor, it cannot alone explain this variance, which is likely to be attributed to a set of variables. These observations could be conceptualized in the context of the “disability paradox,” which refers to the fact that many people with serious and persistent disabilities report that they experience a good QoL when, to most external observers, these individuals seem to live an undesirable daily existence.34 According to other authors, the explanation for this paradox should be sought in the complex balance among body, mind, and spirit upon which QoL depends and which presents a strong subjective nature. Clearly, self-perceived QoL depends on a variety of factors, including familial, financial, individual, interpersonal, marital, professional, physical, spiritual, and social attributes. Any of these may affect an individual’s selfperceived QoL, and from any of these can an individual derive elements of resilience that are not always available for others to cope with the disease and progressively adapt. A lack of awareness about the disease in the patients could represent another possible explanation, possibly a simpler one, for their tendency to overestimate their own QoL with respect to proxies. However, in our sample, the patients showed only a moderate degree of dementia (MMSE on average 15.3 ± 7.5), not a severe degree, and it can therefore be assumed that awareness was at least partially preserved. Moreover, some evidence suggests that degree of insight is unconnected with QoL in early dementia, when insight is maintained.10 The correct approach would likely be to consider these 2 interpretations to be complementary, not mutually exclusive. Concerning the specific variables that seem to account for the primary differences in patients’ and caregivers’ evaluations, results from the regression analysis identified factors related to both patients and caregivers. Patients’ mood disturbances seem to reduce the discrepancy, likely because depressed patients rate their own QoL lower and therefore closer to their caregivers’ evaluations; conversely, independence in performing basic ADL seems to increase the difference. It is possible that being independent in basic activities induces patients to judge their QoL higher than do their caregivers, for whom this aspect could not be as relevant. This independence in basic activities such as bathing, dressing, and feeding relates to a very “intimate” sphere of the individual, which has high value for patients and is perhaps not entirely understood by caregivers, who focus more on instrumental complex tasks. Other factors that appear to be predictive of a greater discrepancy between patients and proxies are the presence Copyright
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of patients’ neuropsychiatric symptoms and caregivers’ depression and perceived burden. Consistent with our data, extensive evidence exists that an increasing behavioral disorder is associated with decreased QoL for caregiver ratings, but the pattern is not repeated for self-reports. This may reflect a decreased patient insight associated with dementia or a differential appraisal of the impacts of emerging behavioral disorder in people with dementia compared with proxies.35 Behavioral and psychological symptoms, in turn, are routinely cited as important predictors of caregiver burden and depression that, according to the literature, are strongly related36,37 and are known to induce caregivers to underestimate the QoL of their relatives.38 Conversely, caregivers’ living arrangements and work status did not seem to be major determinants of QoL in our study, which may indicate that the differences in the ratings between patients and caregivers depend more on psychological/affective variables and coping strategies39 than on objective aspects. The participants in this study presented with moderate cognitive impairment and lived at their home; it is unclear whether these results can be generalizable to people with severe AD or those living in residential care facilities. This sample selectivity could represent an experimental limitation and should be verified in future studies. In conclusion, the results of this study showed that patients and their family members do not always agree in their evaluations of patient’s QoL, so the use of proxies as a substitute when self-reports of QoL data are unavailable should be considered with caution, always considering the presence of potential bias. Despite these difficulties, focusing on the subjective aspects of QoL in chronic neurodegenerative diseases such as dementia is of utmost importance because health care professionals may have a greater chance of intervention into this issue than into other aspects of the disease. Therefore, there is a pressing need for studies in large, representative samples of people with dementia that are both cross-sectional and longitudinal in design to clarify the natural history of QoL in dementia and identify an intervention that can promote it.
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25. Hoe J, Katona C, Roch B, et al. Use of the QOL-AD for measuring quality of life in people with severe dementia—the LASER-AD study. Age Aging. 2005;34:130–135. 26. Conde-Sala JL, Garre-Olmo J, Turro´-Garriga O, et al. Factors related to perceived quality of life in patients with Alzheimer’s disease: the patient’s perception compared with that of caregivers. Int J Geriatr Psychiatry. 2009;24:585–594. 27. Go´mez-Gallego M, Go´mez-Amor J, Go´mez-Garcı´ a J. Determinants of quality of life in Alzheimer’s disease: perspective of patients, informal caregivers, and professional caregivers. Int Psychogeriatr. 2012;24:1805–1815. 28. Leo´n-Salas B, Olazara´n J, Cruz-Ordun˜a I, et al. Quality of life (QoL) in community-dwelling and institutionalized Alzheimer’s disease (AD) patients. Arch Gerontol Geriatr. 2013; 57:257–262. 29. Matsumoto N, Ikeda M, Fukuhara R, et al. Caregiver burden associated with behavioral and psychological symptoms of dementia in elderly people in the local community. Dement Geriatr Cogn Disord. 2007;23:219–224. 30. Andersen CK, Wittrup-Jensen KU, Lolk A, et al. Ability to perform activities of daily living is the main factor affecting quality of life in patients with dementia. Health Qual Life Outcomes. 2004;2:52. 31. Edelman P, Fulton BR, Kuhn D, et al. A comparison of three methods of measuring dementia-specific quality of life: perspectives of residents, staff, and observers. Gerontologist. 2005;45:27–36. 32. Fuh J, Wang S. Assessing quality of life in Taiwanese patients with Alzheimer’s disease. Int J Geriatr Psychiatry. 2006; 21:103–107. 33. Thomas P, Lalloue F, Preux PM, et al. Dementia patients caregivers quality of life: the PIXEL study. Int J Geriatr Psychiatry. 2006;21:50–56. 34. Albrecht GL, Devlieger PJ. The disability paradox: high quality of life against all odds. Soc Sci Med. 1999;48:977–988. 35. Banerjee S, Samsi K, Petrie CD, et al. What do we know about quality of life in dementia? A review of the emerging evidence on the predictive and explanatory value of disease specific measures of health related quality of life in people with dementia. Int J Geriatr Psychiatry. 2009;24:15–24. 36. Bartolo M, De Luca D, Serrao M, et al. Caregiver burden and needs in community neurorehabilitation. J Rehabil Med. 2010;42:818–822. 37. D’Aoust RF, Brewster G, Rowe MA. Depression in informal caregivers of persons with dementia. Int J Older People Nurs. 2014. doi: 10.1111/opn.12043. [Epub ahead of print]. 38. Conde-Sala JL, Ren˜e´-Ramı´ rez R, Turro´-Garriga O, et al. Factors associated with the variability in caregiver assessments of the capacities of patients with Alzheimer disease. J Geriatr Psychiatry Neurol. 2013;26:86–94. 39. Zucchella C, Bartolo M, Pasotti C, et al. Caregiver burden and coping in early-stage Alzheimer disease. Alzheimer Dis Assoc Disord. 2012;26:55–60.
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