May 10, 2010
Spouses caring for partners with dementia at risk of same fate
Husbands or wives who care for spouses with dementia are six times more likely to develop the memory-impairing condition than those whose spouses don’t have it, according to results of a 12-year study led by Johns Hopkins, Utah State and Duke universities.
The increased risk that the researchers saw among caregivers was on par with the power of a gene variant known to increase susceptibility to Alzheimer’s disease, they report in the May Journal of the American Geriatrics Society.
A few small studies have suggested that spousal caregivers frequently show memory deficits greater than spouses who aren’t caregivers. None, however, examined the cognitive ability of caregivers over time using standard, strict criteria to diagnose dementia, a serious cognitive disorder characterized by deficits in memory, attention, judgment, language and other abilities.
To get some answers, Peter Rabins, a professor of psychiatry at the Johns Hopkins School of Medicine, and a team led by Maria Norton, an associate professor in the Department of Family, Consumer and Human Development at Utah State University, examined 1,221 married couples ages 65 or older. These individuals were part of the Cache County (Utah) Memory Study, which since 1995 has identified more than 900 persons with dementia in the community, whose residents topped the longevity scale in the 1990 U.S. census.
Volunteers being screened by researchers for dementia first completed questionnaires to evaluate their cognitive status. Those whose questionnaires suggested possible dementia underwent a comprehensive clinical assessment administered by specially trained nurses and technicians. Finally, a team led by a geriatric psychiatrist and a neuropsychologist evaluated the findings and assigned a diagnosis of dementia where appropriate.
In the sample of 2,442 married persons, the researchers diagnosed 255 individuals with dementia and discovered that individuals whose spouses had already been diagnosed were six times as likely to develop the condition themselves compared to those without an affected spouse.
This increased risk is comparable to the risk of developing Alzheimer’s disease associated with a well-studied gene variant known as APOE ε4, the researchers report. The findings held up even when the researchers accounted for other factors that might influence the risk of developing dementia, such as socioeconomic status.
Norton says that the long-term nature of the new research makes the results different from earlier “snapshot” studies showing memory loss in spousal caregivers. “We know that the declines in memory we saw were real and persistent, not just a point in time where [the subjects] weren’t performing well on tests,” she says.
A strength of the Cache County Study, Rabins notes, is that the findings are highly representative of the community because the vast majority of residents age 65 or older are participating in ongoing research. Earlier studies often relied on results from patients of memory centers and their caregivers, a sample that might not typify the community at large.
Rabins, Norton and their colleagues speculate that the stress of care giving might be responsible for the increased dementia risk for spouses, although more research is needed to identify what that mechanism might be. If their hunch is correct, Rabins says, doctors who treat dementia patients should pay more attention to efforts to decrease stress for spousal caregivers.
“Care giving has positive aspects as well as negative ones. If we can boost the positive aspects and reduce the negative ones, we may be able to reduce a caregiver’s risk of developing dementia,” Rabins says.
Researchers have long been interested in how taking care of a spouse with dementia affects caregivers. Most previous studies have focused on the emotional distress caretakers often experience rather than how their cognitive abilities might be affected.
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