Based on a systematic review of intervention trials in the international literature,6 four measurement constructs were identified for assessing outcomes of intervention studies: quality of life, for example, caregiver burden, coping mechanisms, social support, and marital adjustment; symptoms of psychological distress, such as depression or anxiety; social significance, such as health care utilization, costs to the health care system, or impact on institutionalization; and, social validity such as satisfaction with care processes. Both observational and intervention studies conducted in Canada used one or more of these constructs, with few using the same methods of measuring them.
Most of the located Canadian randomized controlled intervention studies reported limited effects, with no meaningful reductions in caregiver burden.43-46,48,61 While differences sometimes emerged immediately following the intervention,43,46 they did not endure over time. The exception to the above was a multi-centre randomized controlled trial49 that reported significant differences between caregivers in the control group and those in the intervention group in terms of reactions to, and frequency of, behavioural problems, particularly disruptive behaviours.
Methodological problems inherent in intervention studies may partially account for their limited effects. Seven randomized controlled trials have been published in Canada.43-46,48,49,61 The overall sample sizes for the seven studies ranged from 21 to 158, with a mean sample at outset of the study of 67. However, six of the seven trials had high levels of subject attrition43,44,48,49,61 because of death or institutionalization of the care recipient, which may have led to having too few subjects to demonstrate statistically significant results. Several studies mentioned difficulties in recruiting subjects, which could have resulted in non-representative samples of caregivers, for example, those with more time for caregiving or caregivers with moderate levels of burden. Interpreting the practical implications of significant results is difficult because one cannot determine whether the changes are clinically meaningful or relevant to policy.
The above-mentioned problems with intervention studies are consistent with those highlighted by Schulz and colleagues in their review of 43 international intervention studies published since 1996.6 This review reveals that caregiver interventions evaluated to date are short-lived, involve outcomes of minor importance, and do not have an appreciable impact on the quality of life or psychological functioning of caregivers of individuals with Alzheimer's disease. This lack of impact may be due to methodological problems in the studies or to the fact that the interventions do not have the ingredients required to have an important enough effect on caregivers.
One of the obstacles facing Alzheimer's caregiver research in Canada is the limited number of researchers in the field. A national effort should be established to support existing research and to attract newcomers to this field.
Caregiver researchers require more input from interdisciplinary groups in universities and communities (for example, psychiatry, geriatrics, neurology, sociology, community development, and psychology) and more time to spend on their research. Education programs should include more research practicums that allow students to develop advanced research skills. Faculty should also be released from teaching to allow for more time spent on research; the Social Sciences and Humanities Research Council of Canada (SSHRC), for example, has a program through which faculty can apply for release time from courses to pursue research.
National conferences on caregiving would also continue a dialogue related to the learning needs and development of people with research interests in informal Alzheimer's caregiving. Additionally, if the number of intervention studies for caregivers of individuals with Alzheimer's disease is to increase (a need identified in the December 2002 Workshop), opportunities for established social scientists to change their research programs must be established. During their retraining, social scientists would develop skills in areas such as alternative research designs, methods of monitoring, coordinating and conducting randomized controlled trials and related intervention research designs, alternative trial enrollment strategies, randomization techniques, and analyses, such as "intent to treat" analyses. The Canadian Health Services Research Foundation's Career Re-Orientation Award is an example of an initiative to help increase the number of health services researchers.
Finally, research on caregiving of individuals with Alzheimer's disease must include an examination of the best methods for disseminating the results of studies and of collaborating on methods of research. Researchers should incorporate users of research in the research process.