CHICAGO – People who are married from mid- to late life are significantly less likely to develop Alzheimer's disease, while those who remain single face up to an eightfold increased risk, Krister Hakansson said at the International Conference on Alzheimer's Disease.
The protective benefit is probably related to the mental stimulation of living as a couple, said Mr. Hakansson, who is a researcher at the Karolinska Institute in Stockholm.
“Living in a couple relationship is normally one of the most intense forms of social and intellectual stimulation. If social and cognitive challenges can protect against dementia, so should living as a couple,” he said.
The population-based study used data collected in the Finnish Cardiovascular Risk Factors, Aging, and Dementia study. Baseline data were captured from 1972 to 1987. In 1998, follow-up interviews were conducted with 1,500 (72%) of the participants. The average follow-up period was 21 years.
Mr. Hakansson examined data on 1,432 of the follow-up subjects to assess the association of marital status to dementias. In 1998, 832 subjects were married or had live-in partners, 100 were lifelong singles, 111 were single after a separation or divorce, and 389 were single after having been widowed. At follow-up, mild cognitive impairment (MCI) was present in 82 subjects, and Alzheimer's in 48.
Those who were single during midlife were twice as likely to develop cognitive impairment or Alzheimer's as were those who had been married during midlife–a significant difference.
Those who remained single throughout follow-up were even more likely to develop the disorders. Their risk for both MCI and Alzheimer's was three times greater than the risk for those who had a partner from midlife to late life.
The highest risk occurred in those who were widowed in midlife and never remarried. The subjects were three times more likely to develop MCI and almost eight times more likely to develop Alzheimer's.
The results were even more striking when Mr. Hakansson broke down the study group by Apo E4 status. Noncarriers who were divorced or widowed from mid- to late life had a tripling of Alzheimer's risk compared with married noncarriers. But carriers who were divorced or widowed in midlife and never remarried were 25 times more likely to develop Alzheimer's than were carriers with partners.
“A 'socio-genetic' disease model may explain the dramatic Alzheimer's risk increase for the widowed and the Apo E4 interaction effect,” Mr. Hakansson said. The conference was presented by the Alzheimer's Association.