Staying married for life lowers the risk of dementia, according to a new study. Spouses who get married and stay married - without any breaks - are less likely to develop dementia than anyone else.
Conversely, divorced and single people had the highest rate of dementia. Having children also reduces dementia risk - unmarried people were 60 percent less likely to develop the disease if they had kids.
Results led Norwegian University of Science and Technology researchers to suggest dementia is not an inevitable consequence of ageing, and that society could adapt to prevent the disease.
The scientists expected the association would be due to married people leading healthier lives.
Searching for the cause they checked against incidences of smoking, high blood pressure, obesity, physical inactivity, diabetes, psychological problems and having close friends.
However, data from the HUNT study of 150,000 people revealed no health reasons for marriage reducing the chance of dementia developing.
Dr Asta Håberg, professor at the Norwegian University of Science and Technology (NTNU), is not convinced dementia is an inevitable consequence of ageing.
She said: “Exactly what causes dementia is a mystery. This survey indicates that being married and a lower risk of dementia are linked, but we don't know why.
“One theory has been that people who are married live healthier lives, and that this explains differences in the risk of various diseases.
“In this survey, we found no support for health differences between married and unmarried people that would explain the difference in dementia risk.
“Some people have theorised that if you have children, you stay more cognitively engaged. For example, you have to deal with people and participate in activities that you wouldn’t otherwise have to.
“This stimulates your brain so that it possibly works better. That way you build up a kind of cognitive reserve.
“We don’t know whether it’s being married or having children that protects against dementia, or if it’s a case of pre-selection, for example.
“This would mean that people who have a lower probability of developing dementia also have a higher probability of finding a partner and having children.
“But the fact that we have the HUNT Study means that we have a lot of data available that we haven’t yet used to investigate this further.
“It’s common to think that 'if you live long enough, sooner or later you’ll develop dementia'. I'm not so sure I agree with that, given this theory that we may have cognitive reserves.
"It could be that certain conditions might help to build up such reserves, which means that you start with more connections in the brain.
“For example, we’ve observed that education is a factor, and that the more education you have, the better the "reserves" that you build up.
“We’ve dreamt of finding a medicine for dementia for a long time, but we haven’t yet succeeded. So we’re looking at social determinants. What can society do to reduce the risk? The state could facilitate having children, for example."
Dr Håberg said the “reserve” is a part of the “mystery of dementia” and not a structural part of the brain - it doesn’t show up on an MRI, for example.
She added that when a highly educated person gets Alzheimer’s the disease progresses as quickly as it does in anyone else, showing reserves can delay the disease but only until it strikes.
Professor Vegard Skirbekk, of the Norwegian Institute of Public Health, said having a stable family life could reduce genetic vulnerability towards dementia.
He said: “We know that certain genes increase the risk of dementia, but people with these genes can still live to be 90 years old without experiencing cognitive problems.
“You could say that the increased risk inherent in the genes can be regarded as a vulnerability, where having a stable family life might possibly reduce this vulnerability.
“But it shows that being married can have an influence on risk factors. You become more cognitively active, you cope better with adversity and are less subject to stress.
“The partner represents a security that provides a buffer.”
The study, published in Journal of Aging and Health, did not look at those who lived together but weren’t married because there was little data on the subject.
