HomeLarge Type Edition
HOME ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Services
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
PubMed
Right arrow PubMed Citation
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 60:345-349 (2005)
© 2005 The Gerontological Society of America

Physical Disability Contributes to Caregiver Stress in Dementia Caregivers

David G. Bruce1,, Glenys A. Paley1, Pamela Nichols1, David Roberts2, Peter J. Underwood3 and Frank Schaper4

1 School of Medicine and Pharmacology, University of Western Australia, Perth.
2 School of Nursing, Edith Cowan University, Perth, Australia.
3 Department of Environmental Science, Murdoch University, Perth, Australia.
4 Alzheimer's Association of Western Australia, Perth.

Address correspondence to D. G. Bruce, School of Medicine and Pharmacology, Fremantle Hospital, P. O. Box 480, Fremantle, Western Australia 6959, Australia. E-mail: dbruce{at}cyllene.uwa.edu.au


   Abstract
Top
 Abstract
Methods
 Results
 Discussion
 References
 
Background. Previous findings of studies on the impact of physical illness on caregiver health have been inconsistent. The authors wanted to determine whether physical disability, as determined by the SF-12 survey that provides information on both physical and mental health problems, contributes to caregiver stress.

Methods. The authors interviewed 91 primary caregivers (aged 38–85 years) of persons with dementia who had been referred by their family physicians for the first time for formal support services or memory evaluation. Caregivers completed the SF-12 version of the Medical Outcomes Study Short Form Health Survey that generates Mental Component Summary (MCS) and Physical Component Summary (PCS) scores and reported on caregiver stress and concurrent medical conditions and medications.

Results. Most caregivers reported stress (76.9%), having medical conditions (72.4%), or taking medications (67%). The MCS but not the PCS scores were significantly lower than community norms, indicating an excess of disability due to mental health problems. Nevertheless, 40.7% had PCS scores indicating some degree of physical disability. Using multiple logistic regression analysis, PCS scores but not the presence of medical problems were independently associated with caregiver stress.

Conclusions. Chronic disability as assessed by SF-12 PCS scores is independently associated with caregiver stress. These data suggest that caregivers of persons with dementia should be assessed for disabling physical conditions and mental health problems. In addition, reducing the impact of physical disability could ameliorate caregiver stress.

THE potential for mental health problems in family caregivers of patients with dementia is well recognized, particularly in relation to the stress and strain that results from caring for a person with dementia (1). Although the impact of caregiving varies, caregivers of persons with dementia are at increased risk for suffering from mental health disorders including anxiety and depression (2,3). Several studies indicate that the stress of caregiving may also be associated with physical health effects including poorer self-rated overall health (3) and decreased immunity (4), but most studies have found little or no difference in physical illnesses and chronic conditions, and a review of the literature concluded that the evidence linking caregiving with physical morbidity was weak (3). Recently, a large community-based study found that elderly caregivers who reported emotional strain had a high mortality rate compared with similarly aged persons who were not caregivers (5).

Because physical health and mental health are closely linked, research has suggested that caregiver studies should include measures of both types of outcomes (3). To this end, we included the 12-item version (SF-12) of the Medical Outcomes Study Short Form Health Survey as part of our assessment of caregivers of persons with dementia in an ongoing health promotion study aimed at improving dementia care. The SF-12 generates a mental component summary (MCS) score and a physical component summary (PCS) score that provide a broad estimate of disability resulting from mental or physical health problems (6). The SF-12 has been widely used in studies of physical and psychiatric disorders, and local normative data are available. In this investigation, we wanted to determine whether physical health problems contribute to caregiver stress.


   METHODS
Top
 Abstract
 Methods
Results
 Discussion
 References
 
Recruitment
Caregivers of persons with dementia were identified and recruited for a research interview using methods developed in previous studies aimed at identifying successive patients with dementia and caregivers referred for the first time to local geriatric services (7,8). In our health care system, this is virtually always the first time these families have interacted with the formal community support system (7,8). Between April and December 2001, we invited 145 caregivers to be interviewed at their homes. Of these, 92 agreed and were interviewed. Reasons for refusing an interview included caregiver illness and the caregiver being too stressed or too busy. One person refused to complete the SF-12, so this report includes 91 caregivers representing 62.8% of the eligible caregivers identified. All had been caring for relatives with verified dementia for at least 6 months and all identified themselves as the primary caregiver. The Fremantle Hospital Ethics Committee approved the protocol, and all participants signed a consent form.

SF-12
The SF-12 provides a generic measure of health status and disability because it addresses limitations resulting from physical or mental health status. The SF-12 has excellent psychometric characteristics and is recommended for use as an outcome measure for mental health problems (9). The SF-12 has not been used previously in caregiver studies, although the longer version (SF-36) has been (10). The PCS and MCS scores are derived from eight measured concepts (physical functioning, role limitations due to physical health problems, bodily pain and general health for the PCS and vitality, social functioning, role limitations resulting from emotional problems, and psychological distress for the MCS).

Interview
The research interview included questions about the caring role such as the duration and extent of caregiving, the caregiver's knowledge and attitudes about dementia, and how to access services. Demographic data included the caregiver's relationship to the persons with dementia, whether they lived with the patient, estimates of educational level, and household income. Specific questions about caregiver health included: (a) whether they had a health problem (yes/no) and the type of health problem; (b) whether they were taking medications for a health problems (yes/no) and for how long; and (c) whether they were taking medications for an emotional problem or nervous condition (yes/no) and for how long. They were also asked whether they were feeling stressed, to which they could answer yes/no/not sure. The research assistant could clarify that stress could mean feeling anxious, overwhelmed, distressed, agitated, exhausted, under pressure, downhearted, or feeling low.

Data Analysis and Statistics
The MCS and PCS scores were calculated using weightings from the United States that are appropriate in the Australian context (11) despite previous debate (12). The question on stress was dichotomized by combining the "yes" and "not sure" responses (7 participants responded "not sure"). Educational level was assessed by years of schooling, and responses were dichotomized to less than 10 years schooling or not. Income was assessed by annual total family income, and responses were dichotomized to less than $A20,000 or not. The MCS and PCS scores were compared with normative data supplied by the Western Australian Health and Well-being Surveillance System, Department of Health, Western Australia. This population-based survey of more than 10,000 community-living adults aged 18 years and older was administered by telephone and included the SF-12 survey (13).<1?accolade "acc1",1,1,10><1?accolade 1,100,1>Because the age ranges of the caregivers were bimodal (Figure 1)<--?1-->, with a median age of close to 65 years, comparative data were obtained for comparable age ranges (30–65 years and 65–85 years).



View larger version (30K):
[in this window]
[in a new window]
  		Figure 1. Bimodal distribution of ages (in years) in 91 dementia caregivers

 
Statistical analyses were performed using SPSS for Windows (SPSS, Chicago, IL). The PCS and MCS scores are presented as the mean ± SD or by 95% confidence intervals. Two-sample comparisons for normally distributed variables and for MCS and PCS scores were by the Student t test and for non-normally distributed variables by Mann–Whitney U tests. Comparisons of proportions were made using the Pearson chi-squared test, and correlations were made using the Spearman rho test. A significance level of p <.05 was used. Stepwise multiple logistic regression was performed to investigate independent factors associated with the MCS and PCS scores, with variable selection entry of p <.05 and removal at p >.10. Multiple logistic regression analyses using the forward conditional method explored factors associated with caregiver stress, and entry and removal criteria were p <.05 and p >.10, respectively.


   RESULTS
Top
 Abstract
 Methods
 Results
Discussion
 References
 
Description of the Sample
Caregiver ages ranged from 38 to 85 years, and the distribution of ages was bimodal (Figure 1), with the midpoint of the 2 age distributions close to the median age of 62 years. Most were female (71.4%), and 41 were spouses. Nonspouse caregivers included 36 daughters, 10 sons, 1 daughter-in-law, and 3 friends. As expected, child caregivers were significantly younger than spouse (and friend) caregivers (median age, 52.4 vs 76 years; p <.001), although there was overlap (age range for spouses and friends, 49–85 years; age range for children, 38–68 years). Fifty-seven caregivers (62.6%) lived with the dementia sufferer, and this group included all spouses and 34% of child caregivers. Consequently, live-in caregivers were significantly older than non–live-in caregivers (median age, 72 vs 51 years; p <.001). Table 1 includes data on the duration of care and the type and degree of assistance required. Although the duration of symptoms and need for care was lengthy (more than 1 year for the majority), in 79% the referrals from family physicians included a request for an assessment of possible dementia. The majority of the persons with dementia were independent in performing basic activities of daily living but required assistance with cooking, shopping, managing finances, and medications.


View this table:
[in this window]
[in a new window]
  		Table 1. Duration and Burden of Caring for Dementia Sufferers.

 
Physical and Mental Health of the Caregivers
SF-12 MCS scores.-- The mean MCS scores for the caregivers were significantly lower than the state population norms as demonstrated by comparison of confidence intervals (Table 2). In terms of level of mental health–related disability assessed from MCS scores using the method of Sanderson and Andrews (14), 33% had mild disability (MCS scores between 40 and 49), 12.1% had moderate disability (scores between 30 and 39), and 9.9% had severe mental health–related disability (scores <30). There was no significant difference in MCS scores by age, sex, income, education, whether the caregiver lived with the patient, whether the caregiver was a spouse, or by hours of care given by caregivers or activities-of-daily-living dependence of the patients.


View this table:
[in this window]
[in a new window]
  		Table 2. SF-12 Mental and Physical Component Summary Scores in 91 Dementia Caregivers Compared With Western Australian Population Data by Age Groups.

 
SF-12 PCS scores.-- The mean PCS scores were similar to state norms (Table 2), and 40.7% of the caregivers had some degree of disability (PCS score <50), with 29.7% having scores less than 40, representing more severe levels of physical disability. We found no association with sex, caregiver type, income, or by the burden of care (hours of care, or activities of daily living dependence). We noted a significant correlation with age, indicating that older caregivers had worse PCS scores (Spearman rho = –.24, p =.025), and those who had completed less than 10 years of schooling also had significantly lower PCS scores (43.1 ± 11.7 vs 49.3 ± 11.7; t = 2.32, p =.023).

Self-reported stress.-- Most caregivers (76.9%) reported stress associated with the caring role. Self-reported stress was not related to age, sex, caregiver type (live-in or spouse), burden of care (hours of care, activities of daily living dependence), education, or income.

Medical conditions.-- Most caregivers reported having physical health problems (72.4%) and taking medications (67%) (Table 3). Only 4 reported mental health problems, and 15 (16.5%) reported taking medications for nervous conditions. The 4 caregivers who reported mental health problems were female, aged 43–63 years, and reported having anxiety or depression or both. Physical health problems were not related to sex, education, or income but were more commonly reported by older caregivers (by 90% of those older than 65 years vs 58% of younger caregivers; chi-squared = 11.3, p =.001) and by spouse caregivers (85.4% of spouses vs 59.6% of others; chi-squared = 8.1, p =.018). Health problems included arthritis and related conditions (35.2%), cardiovascular risk factors (predominantly hypertension, 34%), cardiac disease (11%), chronic lung disease (8.8%), cancer (4.3%), and a variety of other conditions.

Associations Among Stress, Health Problems, and SF-12 Scores
Table 3 presents the MCS and PCS scores in caregivers according to whether they reported feeling stressed, having medical problems, or taking medications. The MCS scores were significantly lower in those who reported stress, mental health problems, or taking medications for nervous conditions. The PCS scores were also significantly lower in those who reported stress and in those with physical health problems and who were taking any medications.


View this table:
[in this window]
[in a new window]
  		Table 3. Mean (±SD) Mental Component Summary (MCS) and Physical Component Summary (PCS) Scores in 91 Dementia Caregivers Depending on Whether They Reported Feeling Stressed, Having Health Problems, or Taking Medications.

 
Correlates of SF-12.-- Stepwise multiple linear regression analyses were used to determine whether these variables (age, sex, self-reported stress, mental health problem, physical health problem, taking medications for nervous conditions, taking any medications) were independently associated with either the MCS or PCS scores. Stress (Beta = 0.31, p =.002), mental health problems (Beta = 5.31, p <.001), and taking medications for nervous conditions (Beta = 0.26, p =.009) were the only variables independently associated with (poorer) MCS scores (model R2 =.25). Physical health problems (Beta = 0.44, p <.001) and stress (Beta = 0.21, p =.035), but none of the other variables, were independently associated with low PCS scores (model R2 =.25). This latter model was repeated by substituting the medical conditions (arthritic condition, cardiovascular risk, heart disease, lung disease, cancer) for physical health problems. In this model, the PCS scores were independently associated only with stress (Beta = 0.20, p =.028), arthritic conditions (Beta = 0.44, p <.001), and taking medications (Beta = 0.22, p =.021; model R2 =.36).

Correlates of caregiver stress.-- We used multiple logistic regression analysis to explore the relative contributions of mental and physical health to caregiver stress, entering the following variables: MCS scores, PCS scores, mental health problem, taking medications for nervous conditions, physical health problem, and taking any medications. In this model, PCS scores, MCS scores, and reported mental health problem were each independently associated with caregiver stress. Odds ratios (95% confidence interval) were PCS, 1.11 (1.01–.21), p =.023; MCS, 1.13 (1.04–.23), p =.003; and mental health problem, 87.5 (2.37–3221.22), p =.015. This relationship was not altered by substituting specific medical conditions for physical health problems.


   DISCUSSION
Top
 Abstract
 Methods
 Results
 Discussion
References
 
We studied a representative sample of caregivers of persons with dementia at the time of first referral to formal community support services to explore the potential impact of medical illness on caregiver stress using self-reported health status and results of the SF-12 health survey. As a group, they had SF-12 MCS scores lower than population levels, and a substantial proportion (20%) had MCS scores consistent with moderate or severe mental health problems (14). These data are consistent with the findings from studies that show that caregivers are often stressed when they first ask for help (15) and with results of our previous studies using similarly identified participants (7,8).

Most caregivers, especially older ones, reported having physical health problems and were taking medications. There was no excess physical disability in caregivers compared with population levels, although 40% had some degree of disability and many had low PCS scores indicating more severe degrees of disability. The major cause of physical limitation was the category "arthritic conditions," which included self-reported osteoarthritis, previous joint replacement, osteoporosis, and previous fractures. Importantly, we found strong independent associations between caregiver stress and PCS score (i.e., with physical disability). Although it is hazardous to impute causation from cross-sectional associations, it seems likely that physical disability contributed to caregiver stress rather than vice versa (3).

In contrast, the presence of medical conditions was not associated with stress or poor MCS scores. This is consistent with a recent literature review in which the authors concluded that the evidence linking caregiving with physical health problems was weak and inconsistent (3). To our knowledge, physical disability has not been evaluated in this regard. It has been shown that after the death or institutionalization of their relative, caregivers subsequently visit their physicians more often, presumably to attend to previously neglected health needs (16). Most caregiver studies focus on psychosocial issues (17), and recent management guidelines for professionals do not mention the physical health of caregivers (2,18,19). It is conceivable that attempts at lessening the impact of physical disability could benefit the mental health of caregivers.

The presence of reported physical health problems appeared to be associated with better MCS scores in the univariate analysis (Table 3). This counterintuitive result could possibly be explained by the range of ages studied, because older caregivers reported substantially more physical health problems and older persons are less likely to have low MCS scores (6,13). However, the result appears to be due to differences in the younger caregivers only, because younger caregivers who did not report physical health problems had significantly lower MCS scores than did those with physical problems, whereas there was no difference among older caregivers (data not shown). Possibly some younger caregivers are especially vulnerable to mental health problems resulting from caregiving.

A striking feature of our data is the low rate of self-reported mental health disorders (only four cases) and the contrasting high rate of MCS scores indicating serious mental health problems. More than 25% of caregivers had MCS scores less than 42, a level suggested to indicate clinical depression (6) and similar to other estimates of depression prevalence in caregivers of persons with dementia (3). We know that many persons with mental health problems do not consult their family physicians (20). We have reported that caregivers of persons with dementia often have difficulty discussing their problems with their physicians even when they have a good relationship and see them regularly (8). Caregivers of persons with dementia could be at risk for double jeopardy: having a high risk for mental health problems that remain undiagnosed.

The SF-12 appears to be an appropriate assessment tool to assist with assessing caregivers of persons with dementia because of the breadth of the information it provides. It is brief, easy to administer, and has excellent performance parameters, although its utility in the clinical setting may be limited because of the need to apply weights and to calculate scores.

Our study has several important strengths. We used a sampling method that we have successfully employed previously (7,8) and were able to recruit most eligible participants, indicating that the study sample is representative of local caregivers of persons with dementia at the time of initial referral to services in our health care system. In this as in previous studies (7,8), we found that caregivers who declined to participate were usually too stressed or burdened to become involved in research studies, and thus our data probably underestimate the true mental and physical health burden of these persons. Similarly, we studied caregivers relatively early in their caring "career," and it is conceivable that we underestimated the impact of physical health problems, because it has been suggested that health effects from physical disorders take longer to develop (3).

The weaknesses of this study include the lack of controls, and thus our use of published SF-12 data, but we lack data comparison data for the other important medical variables. The study sample is relatively small, with a heterogeneous group of caregivers of different ages and caregiver types. We relied on self-reported medical illnesses, although we would have preferred to have assessed the caregivers' psychological, medical, and functional status independently. Finally, the study is cross-sectional in nature, which precludes any definitive conclusions about causality.


   Acknowledgments
 
Funded by a Health Promotion Project Grant from Healthway, Western Australia.

The authors thank Alison Daly from the Western Australian Health Surveillance Unit for providing comparative SF-12 data.


   Footnotes
 
Decision Editor: John E. Morley, MB, BCh

Received April 16, 2003

Accepted August 4, 2003


   References
Top
 Abstract
 Methods
 Results
 Discussion
 References
 

  1. Donaldson C, Tarrier N, Burns A. The impact of the symptoms of dementia on caregivers. Br J Psychiatry. 1997;170:62-68.[Abstract/Free Full Text]
  2. Eccles M, Clarke J, Livingstone M, et al. North of England Evidence Based Guidelines Development Project: guideline for the primary care management of dementia. BMJ. 1998;317:802-808.[Free Full Text]
  3. Schulz R, O'Brien AT, Bookwala J, et al. Psychiatric and physical morbidity effects of dementia caregiving: prevalence, correlates and causes. Gerontologist. 1995;35:771-791.[Abstract]
  4. Vedhara K, Cox NGM, Wilcock GK, et al. Chronic stress in elderly caregivers of dementia patients and antibody response to influenza vaccination. Lancet. 1999;353:627-631.[Medline]
  5. Schulz R, Newsome JT, Fleissner K, et al. Caregiving as a risk factor for mortality. The caregiver health effects study. JAMA. 1999;282:2215-2219.[Abstract/Free Full Text]
  6. Ware JE, Kosinski M, Keller SD. The 12-item short-form health survey: construction of scales and preliminary tests of reliability and validity. Med Care. 1996;34:220-233.[Medline]
  7. Bruce DG, Paterson A. Barriers to community support for the dementia caregiver: a qualitative study. Int J Geriatr Psych. 2000;15:451-457.
  8. Bruce DG, Paley GA, Underwood PJ, et al. Communication problems between dementia caregivers and general practitioners delay community support services. Med J Aust. 2002;177:186-188.[Medline]
  9. Hickie IB, Andrews G, Davenport TA. Measuring outcomes in patients with depression or anxiety: an essential part of clinical practice. Med J Aust. 2002;177:205-207.[Medline]
  10. Bell CM, Araki SS, Neumann PJ. The association between caregiver burden and caregiver health-related quality of life in Alzheimer disease. Alzheimer Dis Assoc Disord. 2001;15:129-136.[Medline]
  11. Australia Bureau of Statistics (ABS). Mental Health and Wellbeing Profile of Adults. Australia 1997, Catalog no. 4326.0; ABS, Canberra, 1998.
  12. McCallum J, Anderson I. The shorter short form: analysis of SF-12 items in Australian data. In: Australian Institute of Health and Welfare (AIHW) 1996 Integrating Health Outcomes in Routine Health Care. Conference Proceedings, AIHW cat no. HOC-1, Canberra, Australia AIHW.
  13. Daly A, Saunders D, Roberts L. 2000 Collaborative Health and Wellbeing Survey: an overview. Health Department of Western Australia; Perth, June 2001.
  14. Sanderson K, Andrews G. Prevalence and severity of mental health-related disability and relationship to diagnosis. Psychiatr Serv. 2002;53:80-86.[Abstract/Free Full Text]
  15. Audit Commission. Forget Me Not: Mental Health Services for Older People. London: Audit Commission, 2000.
  16. Grasel E. When home care ends—changes in the physical health of informal caregivers caring for dementia patients: a longitudinal study. J Am Geriatric Soc. 2002;50:843-849.[Medline]
  17. Perel VD. Psychosocial impact of Alzheimer disease. JAMA. 1998;279:1038-1039.[Free Full Text]
  18. Doody RS, Stevens JC, Beck C, et al. Practice parameter: management of dementia (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2001;56:1154-1166.[Abstract/Free Full Text]
  19. Cummings JL, Cherry D, Kohatsu NG, et al. Guidelines for managing Alzheimer's disease: Part II. Treatment. Am Fam Physician. 2002;65:2525-2534.[Medline]
  20. Andrews G, Henderson S, Hall W. Prevalence, comorbidity, disability and service utilisation: overview of the Australian National Mental Health Survey. Br J Psychiatry. 2001;178:145-153.[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 Journals of Gerontology Series A: Biological Sciences and Medical SciencesHome page
F. M. Blyth, R. G. Cumming, A. J. M. Brnabic, and M. J. Cousins
Caregiving in the Presence of Chronic Pain
J. Gerontol. A Biol. Sci. Med. Sci., April 1, 2008; 63(4): 399 - 407.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Services
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
PubMed
Right arrow PubMed Citation

HOME ARCHIVE SEARCH TABLE OF CONTENTS