Tying the knot is now tied to healthier aging brains: People who stay married for the long haul may gain some protection from dementia, a new study suggests.
Researchers found that compared with both divorced people and lifelong singles, older adults in a long-term marriage were less likely to develop dementia. Roughly 11% were diagnosed with dementia after age 70, versus 12% to 14% of their divorced or single counterparts.
When the researchers weighed other factors that could affect dementia risk — like education levels and lifestyle habits — long-term marriage was still linked to a protective effect: Divorced and unmarried adults were 50% to 73% more likely to be diagnosed with dementia.
The study is not the first to tie marital status to dementia risk, according to researcher Bjorn Heine Strand, a senior scientist with the Norwegian Institute of Public Health, in Oslo.
"Marriage has been reported to be associated with reduced dementia risk in numerous studies, and our results add to this evidence," Strand said.
The big question is why the link exists. Figuring out the reasons, Strand said, is important — especially considering changing demographics and social norms. The elderly population is growing, meaning more people are at risk of dementia; meanwhile, more people are getting divorced or saying no to marriage altogether.
The findings, published in the Journal of Aging and Health, are based on over 8,700 Norwegian adults whose marital status was tracked from age 44 to 68. Strand's team then looked for correlations with participants' likelihood of being diagnosed with dementia after age 70.
Overall, just under 12% were diagnosed with dementia during the study period, while another 35% developed mild cognitive impairment — problems with memory and thinking skills that may, or may not, progress to dementia.
In general, Strand's team found, marital status was not strongly tied to the risk of milder impairments. But there was a clear relationship with dementia risk: Staying married conferred more protection, versus being divorced (consistently or "intermittently") or unmarried (which counted singles and people who lived with a partner).
The researchers tried to find explanations. Physical health conditions, like heart disease, may contribute to dementia. Similarly, depression, lower education levels, smoking and being sedentary have all been tied to higher dementia risk.
None of those factors, however, seemed to fully account for why divorced and unmarried people had a higher dementia risk.
When the researchers focused on the unmarried group, it did appear that being childless accounted for a good deal of the relationship with higher dementia risk. But that still leaves the question of why.
"Some of the explanation could be that if you have children, you stay more cognitively engaged," Strand said. "For example, you have to deal with people and participate in activities that you wouldn't otherwise have to."
It's theorized, he noted, that such mental and social stimulation — as well as formal education — may help thwart dementia to a degree. People who are more cognitively engaged throughout life may have more "cognitive reserve" — an ability to withstand more of the brain changes that mark the dementia process before symptoms appear.
The findings are consistent with past research on marital status and dementia, agreed Claire Sexton, senior director of scientific programs and outreach for the Alzheimer's Association.
But there are "important caveats," said Sexton, who was not involved in the study.
One is that studies like this cannot prove cause and effect. Beyond that, Sexton said, it's not clear whether findings from older generations would apply to young people today. It's now much more common, for example, for unmarried couples to live together, versus decades ago.
And then there's the bigger picture. Dementia is complicated, Sexton said, and influenced by many factors — including age, genetics, lifestyle habits, physical health and environment. If marital status matters, it would be only one of the variables.
For now, Sexton pointed to the importance of staying socially connected, which may be part of the story when it comes to marital status and dementia.
"Staying socially engaged may support cognitive health," she said. "The Alzheimer's Association recommends engaging in social activities that are meaningful to you, and that you share those activities with friends and family."
In this study, Strand's team did look at whether people reported having "no close friends," and that did not explain their findings.
But in future work, he said, they plan to dig deeper — looking at whether social inactivity, loneliness or general life satisfaction could help explain why marital status is tied to dementia risk.
The Alzheimer's Association has advice on supporting brain health.
SOURCES: Bjorn Heine Strand, PhD, senior scientist, department of physical health and aging, Norwegian Institute of Public Health, Oslo, Norway; Claire Sexton, DPhil, senior director, scientific programs & outreach, Alzheimer's Association, Chicago; Journal of Aging and Health, Nov. 2, 2022, online