Health of Family Members Caring for Elderly Persons with Dementia: A Longitudinal Study

Alzheimer disease and the other primary dementias are major sources of illness in elderly persons. Between 6% and 7% of persons 65 years or older have moderate or severe dementia [1], and among those 85 years or older the prevalence is at least 20% [2]. Most elderly persons with dementia live in the community, usually with the support of a family caregiver. A large body of research now suggests that caring for an elderly family member with dementia can impose chronic stress that may harm the caregiver's emotional and physical health [3, 4]. However, the cross-sectional nature of the existing data makes it difficult to establish the temporal relation between caregiver health and various aspects of the caregiving situation. Furthermore, because of selection factors that differentiate caregivers who abandon the caregiving role from those who do not, the results of cross-sectional studies may be difficult to interpret and generalize [5]. Several studies [6-14] have followed caregivers of elderly persons with dementia for periods of 2 to 30 months. The changes in caregiver health found in these studies were generally small. The absence of a non-caregiving control group in all but one [14] of the earlier studies makes it difficult to compare changes observed among caregivers with changes in comparable persons who were not providing care. Furthermore, many of the earlier studies have been criticized for including caregivers of patients with low levels of impairment [15]. Such caregivers may be in situations that are not particularly stressful, and thus these studies may not constitute a valid test of the hypothesis relating the stress of caregiving to changes in mental and physical health. The principal objective of our study was to estimate the change in depression and physical health during a 1-year period in a group of caregivers for elderly persons with dementia and in a group of comparison participants. We also aimed to examine the relation between changes in caregiver health and certain characteristics of the patient with dementia. Methods Study Design and Participant Recruitment Details of the study design have been reported elsewhere [16]. Briefly, identification of caregivers and comparison participants required two steps: identification of two groups of elderly index patients (one with dementia and one without) and then identification of these elderly patients' close family members. Patients with dementia were recruited at the outpatient Geriatric Assessment Unit of the Jewish General Hospital in Montreal, Canada. The Geriatric Assessment Unit's multidisciplinary team assesses elderly patients with complicated medical, social, and functional problems, many of whom have dementia. Patients are referred to the Geriatric Assessment Unit by their primary care physicians or by a social worker; the referral process is often initiated by family members. Patients were included in the study if they were 55 years or older; had received a clinical diagnosis of dementia, according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders (third edition) [17]; and had a history of cognitive decline of at least 6 months' duration. Patients were excluded if they had been referred to the geriatric unit for preplacement assessment or if they had a major, acute medical problem; 24.1% of potential patients with dementia were excluded for these reasons. Patients having cataract surgery at the same hospital as the Geriatric Assessment Unit were chosen as the source of elderly persons without dementia. Patients with cataracts were excluded if they were younger than 55 years, if they were cognitively impaired (defined as a score of less than 25 on the Mini-Mental State Examination [18]), or if they had a severe or total functional impairment according to criteria of the Older Americans Research and Services questionnaire [19]; 40.8% of potential patients were considered ineligible for these reasons. The demented patient's primary caregiver was defined as the person who had the most responsibility for and provided the most care to the patient. In the case of the comparison group, each patient with cataracts was asked to name the person who currently provided the most daily assistance. Both caregivers and comparison participants were excluded if the person who was identified was not the patient's spouse or child. Structured interviews were conducted in the participant's home by trained interviewers. Only participants who could speak English or French were interviewed. The investigators did not discuss the specific hypotheses of the study with the interviewers. The first interview (time 1) was conducted soon after referral of the patient to the study. The second interview (time 2) was conducted approximately 1 year later (median interval between interviews, 12.4 months; range, 11 to 20 months). The research project was approved by the ethics committee of the Jewish General Hospital. Signed consent was obtained from study participants and a close family member after the nature of their participation was explained. Recruitment and time 1 interviewing took place from 1987 to 1989. Time 2 interviews were conducted from 1988 to 1991. Measurements Depression was measured using the Center for Epidemiologic Studies depression (CESD) scale [20, 21], which includes 20 items, graded on a scale corresponding to the frequency, in the preceding week, of each symptom (ranging from 0, rarely or none of the time to 3, most or all of the time). Possible scores range from 0 to 60. In keeping with previous research [22-26], a score of 16 or more was used to indicate the presence of depression. Aday and Andersen's 24-item checklist, which has been used in studies of health care access [27, 28], was used to quantify physical symptoms occurring in the month preceding the interview. The checklist includes various items, such as coughing, fatigue, headache, weight loss, diarrhea, and chest pain. Consumption of prescription medications by caregivers and comparison participants was determined using the checklist from the Older Americans Research and Services questionnaire [19]. Three questions from this questionnaire [19] were used to assess the caregivers' and comparison participants' perceptions of their overall health: Self-rated health scores were computed as the sums of the scores for the three questions. Participants were asked to indicate whether they had any of the 21 chronic diseases included in the Canada Health Survey questionnaire [29]: the total number of diseases for which the participant answered yes was used as a measure of his or her chronic disease status. The coping efficacy of both groups of study participants was assessed using Olson and colleagues' [30] inventory of family coping strategies. Social support was measured using Cutrona and Russell's 20-item Social Provisions Scale [31, 32]. A three-item index of social support satisfaction, similar to one designed by Stokes [33], was used to quantify the caregivers' assessment of the quality of their social contacts. The caregivers' experience of stressful life events was evaluated using the 34 undesirable events from the Louisville Older Person Events Scale [34]. To determine their lifetime exposure to cigarette smoking, the number of years during which the caregivers smoked was multiplied by the average number of packs of cigarettes smoked per day. The procedure developed for the Established Populations for Epidemiologic Studies of the Elderly surveys was used to measure total alcohol consumption in the month preceding the interviews [35]. The Mini-Mental State Examination [18] was used to assess the severity of the cognitive impairment in the patients with dementia. Possible scores on the 11-item examination range from 0 to 30, with a lower score indicating more cognitive impairment. The functional status of index patients was assessed using the functional subscale of the Older Americans Research and Services questionnaire [19, 36]. The Dementia Behavior Disturbance scale [37] was used to quantify the frequency of behavioral problems in the patients with dementia. Analysis Change scores were computed for both depressive symptoms and physical symptoms by subtracting the value at time 1 from the value at time 2. Thus, a difference with a positive sign indicated worsening of the caregivers' level of depression or physical symptoms, whereas a difference with a negative sign indicated an improvement. Analysis of variance was used to test the difference between caregivers and comparison participants with respect to the change in the dependent variables, after adjusting for potential confounding variables. In these analyses, the change score was the dependent variable, caregiving status (1, caregiver; 0, comparison participant) was the independent variable, and the time 1 value of the dependent variable was included as a covariate. For depressive symptoms, the following covariates were also included: sex (1, female; 0, male), ethnic group (1, Jewish; 0, other), education (1, high school completed; 0, high school not completed), age, number of chronic diseases, number of stressful life events in the preceding 6 months, coping score, social provisions score, and support satisfaction score. For physical symptoms, two covariates were included in addition to those listed above: lifetime exposure to cigarette smoking (in pack-years) and number of ounces of alcohol consumed in the previous month. Multiple Classification Analysis, available in the Statistical Package for the Social Sciences [38], was used to estimate the mean change among caregivers and comparison participants after adjusting for covariates. Multiple Classification Analysis uses the results of the analysis of variance procedure to compute adjusted mean values of the dependent variable in subgroups defined by the categories of the independent variable(s). Changes in caregiver health were considered in relation to four