Elderly people who care for a spouse who has dementia are at increased risk of developing dementia themselves, a study finds. The stress of attending to a mentally incapacitated spouse may somehow contribute to the added risk, scientists report in the May Journal of the American Geriatrics Society.
sciencenewsPrevious studies have shown that chronic stress leads to increased levels of the hormone cortisol in the body, which can suppress immunity, says study co-author Peter Rabins, a psychiatrist at Johns Hopkins School of Medicine in Baltimore who teamed with researchers at Utah State University in Logan to do this study. “It’s long been thought that this might have adverse outcomes psychologically and physiologically.”
Taking care of a spouse with dementia takes a toll in other ways as well, Rabins says. “Caregivers often complain that they lose their friends,” he says, because they don’t have time to socialize. But the biological mechanisms that might link these challenges to heightened dementia risk remain unclear.
In the new study, the researchers assessed the mental status of 1,221 Utah couples who had agreed to be part of a community-wide health study that started in 1995. The men averaged age 76 and the women 73 at that point, and 95 percent had been married for more than 20 years. Researchers tracked these couples’ mental status with up to four exams over the next decade with a median followup of 3.3 years. No participants in this analysis had dementia at the start.
During the followup years, 229 people found themselves caring for a spouse with dementia. The caregivers were six times more likely to develop dementia themselves compared with people whose spouses did not develop dementia. The researchers accounted for differences between the couples in age, education, socioeconomic status and the presence of variants in the APOE gene that can increase risk of Alzheimer’s disease.
While this is the first study to look at actual dementia risk in spousal caregivers, other research has documented an array of physical and mental problems associated with caregiving. These include depression, sleep problems, less exercise and unhealthy diet, says Peter Vitaliano, a psychologist at the University of Washington School of Medicine in Seattle, writing in the same issue of the Journal of the American Geriatrics Society. All these conditions may be risk factors for dementia, he notes.
In the new study, the authors point out that some of the increased risk of dementia in caregivers may be due to shared environment. The couples had been married on average for 49 years upon enrollment in the study. But what those shared environmental risk factors might be remains unknown.
One other possible contributor to this dementia risk could be the tendency of people who are prone to distress or mental illness to find and marry one other, Rabins says.
Bruce McEwen, a neuroscientist at Rockefeller University in New York City, says that in the future researchers might do well to investigate whether caregiver spouses who have less social support — or who are just more isolated — might be at the most risk.