What role does marital status play in dementia risk?

By Dr. Chinta SidharthanReviewed by Danielle Ellis, B.Sc.Mar 23 2023

In a recent study published in the Journal of Aging and Health, researchers in Norway and the USA examined the association between trajectories of marital status in midlife and the prevalence of mild cognitive impairment and dementia. The study focused on patients aged 70 and above through a large population-based study in Norway.

Study: Marital Histories and Associations With Later-Life Dementia and Mild Cognitive Impairment Risk in the HUNT4 70+ Study in Norway. Image Credit: Dragana Gordic / Shutterstock

Background

A significant portion of the older population is affected by dementia, and the numbers are expected to increase significantly by 2050 due to the expanding aging population. With limited pharmacological treatments available for dementia, recent research focuses on the effectiveness of reducing social and health-related risk factors in preventing or delaying dementia or mild cognitive impairment.

Among the factors linked to reduced dementia risk in older age is marital status in later life, where marriage protects against dementia in old age, and single status increases dementia risk with aging.

The recent decades have seen a significant shift in social norms, such as living arrangements and partnerships, with increased divorce, cohabitation, and the number of single individuals. This highlights a need to better understand the association between marriage and dementia risk.

About the study

In the present study, the researchers used information from a Norwegian longitudinal survey to formulate marital history measures and analyze the association of these measures with diagnoses of dementia and mild cognitive impairment in the later stages of life.

Since studies have indicated that the dementia-related health benefits of marriage are not evident in midlife, the researchers used the longitudinal dataset obtained from an ongoing, large-scale population survey in Norway. Researchers examined the association between midlife marital status and the risk of mild cognitive impairment and dementia in old age.

The researchers hypothesized that compared to those who have been widowed or divorced or are unmarried, those who have been married for an extended period would have a lower risk of dementia. While mild cognitive impairment could progress to dementia, it is often not seen to decline and has been observed to revert to normal conditions in some cases. Therefore, the association between marital status and mild cognitive impairment was hypothesized to be similar to that predicted for dementia but with weaker associations.

Based on previous studies, the researchers also hypothesized that the beneficial effects of marriage in reducing the risk of dementia would be more for men than women. Furthermore, the study also aimed to determine if factors such as the number of children, risk factors such as obesity, hypertension, diabetes, smoking behavior, psychological stress, and lack of socializing could explain the association between marital status in midlife and the risk of dementia in old age.

Results

The results reported that the prevalence of dementia was the lowest among those who were continuously married, and was the highest for those who were unmarried, followed by those who were continuously divorced and intermittently divorced.

The association between mild cognitive impairment and marital status was weaker than for dementia. No association between sex and the beneficial effects of marriage on dementia risk was observed.

Those widowed or intermittently married (predominant status was married, albeit intermittent) had a similar risk of mild cognitive impairment and dementia as those who were continuously married. The risk of mild cognitive impairment was high only for the unmarried group compared to the continuously married group, after adjusting for sex, age, and education.

Compared to those who were continuously married, the unmarried and continuously divorced groups had a 43% and 66% increase in the risk of dementia, respectively, after adjusting for education levels, age, and sex. A sensitivity analysis with a different age window for marital status did not result in a significant difference in dementia risk for the various groups.

 Furthermore, the findings suggested that 60% of the dementia risk for the unmarried group was associated with not having children, while the remaining 40% was attributed to factors not including diabetes, smoking, hypertension, obesity, mental stress, physical inactivity, and not having friends.

Conclusions

Overall, the findings reported that being continuously married in midlife was linked to a lower risk of dementia in old age, and being unmarried or intermittently or continuously divorced could increase the risk of dementia in the later stages of life.

The authors believe that while they cannot identify causal effects, these results highlight the possible mediating roles of social factors, having children, and marital status in improved cognitive health in later life. Furthermore, given the changing social situations and increased rate of divorces, these results could imply a higher healthcare burden related to dementia in the future.