Marriage and Cohabitation Reduced Alzheimer's

Researcher Says Dementia Prevention Could be Due to Socialization

Jul 26, 2009

People thinking about getting married or divorced have many pros and cons to consider. Here’s something they might not have thought of: living alone might increase their risk of Alzheimer's dementia later on.

Cardiovascular Study (CAIDE) Subjects Re-Analyzed

These results came from the cardiovascular risk factors, aging, and dementia (CAIDE) study. Two thousand subjects in Finland were evaluated in 1972 and 1987. After about 20 years, they were tested for possible dementia. (Alzheimer's is the most common form of dementia.) About 1400 were found and available for the evaluation. Of these, 143 had significant cognitive (brain function) loss, 82 had mild cognitive loss, and 48 had Alzheimer's.

“Marriage” Includes Cohabitation

Investigators grouped all couples who cohabitated as “married.” They then formed three groups: married both in midlife and later life; married in midlife, not later; and not married in midlife or later life.

Living Alone Increases Risk of Impairment

An analytic model adjusted for known risks for Alzheimer’s such as blood pressure, gender, education and APOE status. Results showed that those living alone in later life were more likely to have cognitive impairment. This was especially true for widowed people.

Those who lived alone in midlife were twice as likely to have cognitive impairment in later life.

While those living alone in midlife had double the risk of cognitive loss later, a subgroup had an even higher risk. Those who continued to live alone – did not marry or live with a partner – had almost three times the risk later in life.

If being single in midlife was due to death of a partner, and the person did not marry again, the risk of later Alzheimer's was even greater.

Social Interaction May be Key

The study's lead investigator suggested that marriage (or cohabitation) encourages more social interaction, shown in other studies to be associated with less Alzheimer's. Mouse studies have shown a link that supports socialization as beneficial. Mice who were exposed to more mice had less build up of amyloid in their brains. Amyloid is the abnormal brain protein that is widely felt to cause Alzheimer's.

It is possible that some factor other than cohabitation caused the effect, increased risk of cognitive impairment. For example, some genetic defect may lead to a personality that prefers non-marriage and also predisposes to dementia in later life. However, this would not explain why widows, who were not responsible for their widowhood, would be more likely to develop cognitive impairment.

The study adjusted for other known risk factors such as APOE genotype (a genetic risk for Alzheimer's). All the subjects lived in Finland, so factors such as diet and environment can be different than other countries, and the findings may not be generalizable. The results of the study were associations – living alone in midlife was associated with more cognitive loss later – and did not prove cause and effect.

The copyright of the article Marriage and Cohabitation Reduced Alzheimer's in Marriage is owned by James Cooper. Permission to republish Marriage and Cohabitation Reduced Alzheimer's in print or online must be granted by the author in writing.

Aug 9, 2009 11:27 AM

Guest :

Did anyone explore the possibility that people with chronic illnesses that lead to dementia are more likely to be divorced or widowed at mid-life or living alone in old age? Any kind of chronic illness is bound to reduce a couple's quality of life and increase the odds of divorce. A sick partner is much less desirable than a well partner.
As far as widowhood, has anyone explored the effect of grief on people's health? And aren't most women likely to end up being widows in old age, since women generally live longer than men? Was that factor taken into account in this study?
It just seems strange that marriage is touted as being so great for people's health, yet apparently people don't enjoy being married that much; otherwise the divorce rate wouldn't be so high. These studies are probably revealing something else besides a beneficial "marriage effect" on health.