Overview: Long-term, uninterrupted marriage from middle to old age is associated with a lower risk of developing dementia.
If you are married continuously for many years in middle age, you have a lower risk of developing dementia in old age, according to a recently published study based on data from HUNT Study health surveys in Nord-Trøndelag.
“Being married can influence risk factors for dementia,” says Vegard Skirbekk of the Norwegian Institute of Public Health (NIPH/FHI).
The researchers looked at different types of marital status in people over a 24-year period — from ages 44 to 68 — and examined whether this status was related to a clinical diagnosis of dementia or mild cognitive impairment (MCI) after age 70.
The results show that the group that was continuously married throughout the entire period had the lowest incidence of dementia.
The highest incidence was found in divorced and single people.
Children reduce the risk
Asta Håberg is a physician at St. Olav’s Hospital and a professor at NTNU, as well as a researcher at NIPH/FHI. She says the results of the study contain surprises.
“What exactly causes dementia is a mystery. This study indicates that being married and a lower risk of dementia are linked, but we don’t know why,” says Håberg.
“One theory is that people who are married live healthier lives, and that this explains the differences in the risk of various diseases. In this study, we found no support for health differences between married and unmarried people that explain the difference in risk of dementia.”
In the HUNT survey, about 150,000 people in Nord-Trøndelag consented to health information being made available for research. The researchers used this data to test the incidence of dementia against health factors such as smoking, high blood pressure, obesity, physical inactivity, diabetes, psychological problems and having close friends.
“We thought these factors would mean something, but they didn’t explain anything,” says Håberg.
However, the researchers found that having children was significant and reduced the risk of dementia by 60% among the unmarried people in the study.
“Some people have theorized that having kids keeps you more cognitively engaged. For example, you interact with people and participate in activities you shouldn’t otherwise. This stimulates your brain and may make it work better. This way you build up a kind of cognitive reserve,” says Håberg.
Lots of unused data
This “reserve” in the brain is not structural. It does not show up on an MRI scan or by opening the brain and looking inside. It’s part of the “mystery of dementia.” But Håberg hopes to reveal part of the mystery through this study.
“We don’t know whether being married or having children protects against dementia, or whether it is, for example, a case of pre-selection. This would mean that people with a lower chance of developing dementia also have a higher chance of finding a partner and having children. But the fact that we have the HUNT study means we have a lot of data available that we haven’t used to explore this further yet,” says Håberg.
As a doctor, she is not convinced that dementia is an inevitable consequence of aging.
“It’s common to think that ‘if you live long enough, sooner or later you’ll get dementia’. I’m not so sure I agree, given this theory that we might have cognitive reserves.”
It may be that certain conditions help to build up such reserves, starting you with more connections in the brain. For example, we have seen that education is a factor, and that the more education you have, the better the ‘reserves’ you build up.
And yet, if a highly educated person gets Alzheimer’s, the disease progresses just as fast as anyone else. So the reserves have a delaying effect – but only until the disease hits.
Make it easier to have children
The study results are part of the research project REFAWOR (Cognitive reserve work and family), funded by the NIH in the US, which is part of the “Changing lives, changing brains” program under the auspices of the Norwegian Institute of Public Health.
REFAWOR has a budget of almost three million euros and wants to investigate how changes in living and working conditions influence the risk of Alzheimer’s, dementia and cognitive disorders in the elderly. These diseases are expected to triple by 2050.
The researchers now take a closer look at the significance of having children for the risk of dementia, the type of work people have and how retirement age can influence the risk.
Dementia is a collective name for various diseases and injuries in the brain. Memory weakens and the ability to think logically is impaired. Eventually, it becomes difficult to manage on your own and perform daily activities. There is currently no medical treatment for dementia available.
“We have long dreamed of finding a cure for dementia, but we have not yet succeeded. So we look at social determinants. What can society do to reduce the risk? For example, the state could facilitate having children,” says Håberg.
Genes can make us more susceptible
One of the next steps is to look at genetic connections, says Skirbekk.
“We know that certain genes increase the risk of dementia, but people with these genes can still live to age 90 without experiencing cognitive problems,” he says.
“You could say that the increased risk inherent in the genes can be considered a vulnerability, where having a stable family life could potentially reduce this vulnerability.
He emphasizes that this research says nothing about the biological mechanisms behind dementia.
“But it shows that being married can affect risk factors. You become more cognitively active, deal better with setbacks and are less subject to stress. The partner stands for a certainty that provides a buffer.”
The work has been published in the Journal of Aging and Health.
The study does not examine whether there is a difference between an unmarried versus a married couple. Less than one percent of the unmarried people in the survey lived with a partner.
“There are very few cohabitants in this age group in HUNT,” says Håberg.
About these relationships and news about dementia research
Writer: Ingebjørg Hestvik
Contact: Ingebjørg Hestvik – NTNU
Image: The image is in the public domain
Original research: Open access.
Marriage histories and associations with later life dementia and mild cognitive impairment in the HUNT4 70+ study in Norway by Vegard Skirbek et al. Journal of Aging and Health
Marriage histories and associations with later life dementia and mild risk of cognitive impairment in the HUNT4 70+ study in Norway
Goals: Previous studies suggest that being married later in life protects against dementia, and that being single at an older age increases the risk of dementia. In this study, we investigate the trajectories of middle-aged marital status and their association with dementia and mild cognitive impairment (MCI) at the age of 70 years and older, using a large sample from the Norwegian population.
methods: Based on a general population sample linked to population registers (N = 8706), we used multinomial logistic regression to examine the associations between six types of marriage trajectories (single, permanently divorced, occasionally divorced, widowed, married continuously, occasionally married) between the ages of 44 and 68 years from national registries and a clinical dementia or MCI diagnosis after age 70. We estimated relative risk ratios (RRR) and used mediation analyzes that adjusted for education, number of children, smoking, hypertension, obesity, physical inactivity, diabetes, mental problems, and having no good friends in middle age. Reverse probability weighting and multiple imputations were applied. The population attributable fraction was estimated to assess the potential reduction in dementia cases due to marital histories.
Results: A total of 11.6% of the participants were diagnosed with dementia and 35.3% with MCI. The prevalence of dementia was lowest among the continuously married (11.2%). Adjusted for confounders, the risk of dementia was higher for single (RRR = 1.73; 95% CI: 1.24, 2.40), continuously divorced (RRR = 1.66, 95% CI: 1.14; 2.43) and periodically separated (RRR = 1.50). ; 95% CI: 1.09, 2.06) compared to continuously married. Overall, the marriage trajectory was less associated with MCI than with dementia. In the counterfactual scenario, where all participants had the same risk of being diagnosed with dementia as the continuously married group, there would be 6.0% fewer cases of dementia.
Discussion: Our data confirm that staying married into middle age is associated with a lower risk of dementia and that divorced people account for a significant proportion of dementia cases.