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Study shows unmarried people have lower risk of dementia

A surprising new study shows that unmarried people had a much lower risk of dementia compared to married people. I am surprised by this finding, along with, I suspect, many readers of this article.

This study will be contrary to the expectations from the commonly held belief that marriage is protective against cognitive decline, dementia, and Alzheimer’s disease.

As I usually do, I will review this paper and see if the results tell us anything about being unmarried and the risk of dementia.

selective focus photography of silver colored engagement ring set with pink bow accent on throw pillow

Photo by Pixabay on Pexels.com

What are dementia and Alzheimer’s disease?

Before I proceed, it’s important to describe Alzheimer’s disease (AD). It is a chronic neurodegenerative disease that usually starts slowly and worsens over time. It accounts for 60-70% of dementia cases, even though the terms are sometimes used interchangeably. Alzheimer’s disease is a form of dementia.

Amyloid plaques, phosphorylated tau tangles, and neurofibrillary tangles are generally easily visible pathologies that can be observed by microscopic analysis of brain tissue from autopsies of those potentially afflicted by AD. These plaques and tangles seem to affect nerve functioning. Despite these observations, the precise pathophysiology, or development, of the disease is not known.

Since amyloid plaques are often identified in patients with Alzheimer’s disease, a large amount of research is focused on attacking those plaques as a way to reverse the effect on nerves, which leads to AD.

The causes of AD are unknown (notice how much we do not know about this disease). However, it is speculated that it is mostly genetically related, with a large number of genes that underlie this relationship. Despite the internet tropes, there is no rigorous evidence that aluminum causes AD – I wish this belief went away fast.

Since we have no clear understanding of the etiology and pathophysiology of AD, few treatments are available today. Some drugs target the amyloid plaques but have not been shown to change the outcomes of AD.

A couple of medications help manage some of the disease’s symptoms, but they are certainly not cures, and they are very expensive. Several drugs at the earliest stages of development may hold out hope of treating the underlying disease, but we are years away from knowing if they work or not.

One more thing that needs to be made clear. There are no biological tests for Alzheimer’s disease — usually, you can only find the amyloid plaques and other pathologies in post-mortem autopsies. Unfortunately, in the absence of an autopsy, clinical diagnoses of AD are “possible” or “probable”, based on other findings, such as memory tests and other methods.

positive senior man in eyeglasses showing thumbs up and looking at camera

Photo by Andrea Piacquadio on Pexels.com

Unmarried and the risk of dementia paper

In a paper published on 20 March 2025 in Alzheimer’s & Dementia, Selin Karakose, PhD, Florida State University College of Medicine, Tallahassee, FL, and colleagues, used data for 24,000 older adults from the Health and Retirement Study from 2000 to 2014. Participants had annual evaluations at specialized dementia clinics. The study findings may indicate delayed diagnoses among unmarried people or could question the assumption that marriage protects against dementia.

The study evaluated data from the National Alzheimer’s Coordinating Center (NACC), an ongoing longitudinal study of participants recruited from Alzheimer’s Disease research centers throughout the USA. At each annual visit, clinicians assessed cognitive status using neuropsychological tests and clinical examinations. Dementia diagnoses were based on the Clinical Dementia Rating scale.

Individuals who were separated were included in the divorced group, and individuals living with a domestic partner were included in the married group.

Here are the key results:

In models adjusted for age and sex, never-married individuals had a 40% lower risk of dementia than married older adults.

Divorced individuals had a 34% lower risk

Widowed older adults had a 27% lower risk.

The authors concluded:

The present study examined the association between marital status and the risk of dementia in a US sample of older adults followed for up to 18 years. Accounting for age and sex, we found that widowed, divorced, and never-married individuals had ≈ 50% or lower dementia risk relative to their married counterparts. The associations held for divorced and never-married older adults after controlling for age, sex, race, ethnicity, education, living alone, depression, smoking behavior, diabetes, hypertension, obesity, diagnostic form, participant’s referral source, reason to visit ADRC (Alzheimer’s Disease Research Center), and APOE ε4 (apolipoprotein E).

Summary

I’ve written around 100 articles about various lifestyle effects on dementia and Alzheimer’s disease. Getting your shingles vaccine is one of the newest.

However, I would have never guessed that being unmarried would be one of the stronger ways to reduce the risk of dementia and Alzheimer’s disease.

The study has some weaknesses. The participants may not represent the US population — most of the sampled population was white and married. Other factors, like financial stress and social connections, may have played a role in the difference, but were not accounted for in the analysis.

The study also has some significant strengths. It is a large study that included rigorous cognitive assessment and clinical diagnoses of dementia in specialized centers across the United States. The study also included older ages, assessment of dementia risk factors, long follow-up, and analyses of cause-specific dementia.

One of the most important issues to address in showing that there is causality between marital status and risk of dementia is to show biological plausibility. In other words, what plausible biological mechanisms could cause such a link?

One reason could be that unmarried individuals may have more social connections than married individuals. On the other hand, I might argue that people who are married have more social connections. It is also possible that unmarried individuals have delayed diagnoses of dementia simply because they don’t have a partner who might notice cognitive decline.

Further research is necessary to determine if this is a valid correlation. And if it is confirmed, more studies will be necessary to determine the reasons.

I guess those who are unmarried an older age may have a reason to celebrate.

Citations

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Michael Simpson

Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!