DEAR DOCTOR: I recently read that marriage reduces the risk of mental decline in old age. I'm not sure I buy it. But, assuming it's true, why would that be?
DEAR READER: You're likely referring to a recent study in the journal Neurology, Neurosurgery and Psychiatry that combined data from 15 studies with a total of 812,047 people. In each of the studies, the authors looked at the marital status of participants over age 65 and the overall rate of dementia. Most of the studies were performed in Europe, with the largest -- 750,129 participants -- conducted in Sweden. The average age of all participants was 73 years.
The data did suggest a protective effect from marriage, with lifelong single people having a 42 percent higher risk of dementia than married people, and widowed people having a 20 percent higher risk. The researchers found no differences based on gender.
Interestingly enough, in the primary analysis, divorced individuals had the same rates of dementia as their married counterparts. But, notably, when researchers looked at data from the large Swedish study, they found twice the risk of dementia among divorced people who began the study between the ages 50 and 64 and 1.4 times the risk among divorced people ages 64 to 75.
There's no one good explanation why marriage would benefit brain function. It may be that marriage challenges a person. In the needed conversation between the partners in marriage, there are differences of opinion, a necessity for mental flexibility, and a level of stress that requires people to go outside of their comfort zones and challenge their brains. It also may be that married life leads to social interactions with other couples or with in-laws, which lead to greater human interaction -- even if all of them aren't pleasant.
Obviously, marriage tends to provide greater social support. To know that somebody cares about you can reduce depression and anxiety, which also may lead to a greater desire to take care of yourself both physically and mentally. This self-care, in turn, may help ward off dementia. That could be why being widowed is associated with a greater risk of dementia, compared to being married.
Then there are the health aspects of marriage. Other studies have found that marriage is linked to increased longevity, which suggests that dementia risk may be reduced through a decreased rate of illnesses and habits that can increase the likelihood of dementia.
Ultimately, although marriage may provide a modest benefit in warding off dementia, I would look at this data with a grain of salt. Many people who have never been married, who have been divorced or who are widowed obviously lead long lives without any trace of dementia. Certainly, no one would recommend an unhappy marriage as a possible protective factor against dementia risk.
Further, the recently published data are from older individuals. The study's ultimate conclusion may be applicable to a different world than the one in which we currently live. In this day and age, society is more accepting of a single life; our current world may be stimulating and protective enough on its own.
(Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.)
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