Are married people healthier and are they healthier because they are married? Those claims have been made so often that many people accept them as uncontested truths. But recent studies, often more sophisticated methodologically than the ones from the past, are challenging that belief.

Just published this year (2025) was an 18-year study of dementia among more than 24,000 older adults. All of the unmarried adults – whether divorced or widowed or never married – were at lower risk of developing dementia than the married adults. Their risk was at least 50 percent lower. The people who had always been single (never married) had the lowest risk of all, though the difference between them and the other unmarried groups was not statistically significant.

Selin Karakose of Florida State University and her colleagues reported their findings in “Marital status and risk of dementia over 18 years: Surprising findings from the National Alzheimer’s Coordinating Center,” in Alzheimer’s & Dementia.

In the study, 24,107 participants between the ages of 50 and 104 (average was 72) were assessed every year for as many as 18 years. Each time, they took neuropsychological tests of cognitive status and they were also evaluated by clinicians. Results showed that the people who were not married were less at risk than the married people for dementia, Alzheimer’s or Lewy body dementia.

When the participants showed up for the first time, some of them already had mild cognitive impairment. Of those, it was again among the unmarried that their mild impairment was less likely to progress to dementia.

During the study, some of the married participants became widowed. Those widows and widowers were less likely to develop dementia than the participants who stayed married.

The researchers examined many other factors that could be relevant, such as age, sex, race, education, smoking and other measures of physical and mental health. The key findings emerged over and over again: Unmarried people are less likely to develop dementia than married people. There was some variation in the size of that difference, but it was small. For example, the advantage of single men over married men was a bit greater than the advantage of single women over married women. The unmarried men were especially unlikely to develop dementia.

Why Are Unmarried People So Unlikely to Experience Cognitive Decline?

The researchers could not say definitively why the unmarried people were less likely to develop dementia than the married people, but they did have some suggestions. They based them on a finding that has been replicated many times – that single people are better at maintaining their social ties – but not acknowledged often enough in medical journals.

Here’s what Selin Karakose and her colleagues said: “Never married individuals are also more likely to socialize with friends and neighbors and are more likely to engage in healthier behaviors than their married counterparts. Married individuals tend to have less social integration and are engaged in less frequent and lower-quality interactions in their networks compared to their unmarried counterparts. These positive aspects of well-being and social ties may potentially serve as protective factors against dementia over time.”

In an interview with MedPage Today, Karakose added that single people may be more self-reliant. That too could help account for their more enduring cognitive abilities.

I’d add, from my research for Single at Heart, that single people may have more psychologically rich lives characterized by a variety of interesting and unique experiences. Leading that kind of life may well keep people cognitively sharp.

What About the Claims That Married People Are Healthier?

Many studies that supposedly support the claim that marriage makes people healthier compare people who are married to people who are not married at one point in time. If married people do in fact score as healthier, that is not evidence that they are healthier because they are married and have that special spousal relationship. It is a correlation; it doesn’t prove causation.

For example, maybe in some of those studies, married people are healthier not because of any special relationship with their spouse but because they have more access to health insurance and high-quality health care.

The implication left dangling in studies in which married people score as healthier (or happier or just about anything else) than unmarried people is that if only those unmarried people would get married, they would get healthier. Following the same people over time, to see if they do in fact become healthier after they marry is a better study methodologically (though it still falls short of establishing causality).

Lots of studies show that people who marry do not become lastingly happier than they were when they were single. The same may be true for health. For example, a 16-year study of more than 11,000 Swiss adults found that marriage did not protect people from declining health. In fact, when the participants got married, they reported slightly worse health than when they were single. Over time, as their marriage progressed, their health declined.