Feeling part of a community was linked to a slower pace of aging read from a brain scan

People who feel good about their lives tend to live longer and get fewer chronic diseases. But "well-being" covers several different things. Being satisfied with life and in a good mood is one. Having a sense of purpose, growth and control over your life is another. A third, called social well-being, is about how you see your place in the wider world: whether you feel you belong to a community, are accepted by it and contribute something to it.

Earlier studies linked well-being to slower biological aging, but they mostly lumped these kinds together and measured aging with blood tests of DNA methylation. This study separated the three and measured aging in a new way: from a single brain scan.

What they did

The team used data from the Midlife in the United States (MIDUS) study, a long-running national survey. They included 213 adults, aged 26 to 95 with an average age of 56, who had answered questionnaires on well-being and later had a brain MRI scan, on average 3.8 years after the survey.

From each scan they calculated DunedinPACNI, a score developed by other researchers. It was trained on 860 participants of the Dunedin Study, who were examined repeatedly between ages 26 and 45, to estimate from the shape and size of brain regions how fast a person's body is aging overall, based on how quickly 19 measures of heart, metabolism, kidney, immune, dental and lung health changed over the years. A higher score means faster aging.

Statistical analysis sorted the questionnaire answers into three kinds of well-being: feeling good (life satisfaction and mood), private well-being (purpose, growth, autonomy, self-acceptance) and social well-being. The team then checked how each one related to the brain-based score, adding adjustments step by step: first for age, sex, race and income and education; then for body mass index, chronic diseases, smoking, drinking, exercise and mentally stimulating activities; and finally for marriage and the number of people someone regularly sees.

What they found

• Social well-being stood out. Higher social well-being went with a lower (slower) pace-of-aging score at every step of adjustment, including the full model.
• The others faded. Private well-being, and to a lesser degree feeling good, were linked to a slower pace only before health and lifestyle were taken into account. After that, the links disappeared.
• A second method agreed. A computer method that picks the most useful predictors on its own kept social well-being in 83% of repeated runs, compared with 14% for private well-being and under 5% for feeling good.
• Number of friends did not matter. Being married and the size of a person's social network were not linked to the score. What counted was how people felt about their place in the community.
• A hint about volunteering. In an exploratory analysis, people who spent more hours a month volunteering had higher social well-being, which in turn went with a slower pace of aging.

Other things went with a faster score, as expected: older age, higher body mass index and more chronic diseases. Higher income and education went with a slower one.

What to keep in mind

• Reverse causation is possible. The authors note that although well-being was measured before the scan, people who are aging more slowly may simply stay healthier and more active, and so feel better about their social lives.
• A modest, select sample. 213 people is not many. Most were White, and the authors say those who stay in MIDUS and have brain scans tend to be younger, healthier and better educated.
• A new yardstick. DunedinPACNI is a recent tool, and different measures of biological aging often only partly agree with each other.
• Volunteering is a hint only. Volunteering and well-being were measured at the same time, and the authors stress that the results do not show a causal mechanism.
• Not yet peer-reviewed. The paper is a preprint and was not registered in advance.

Why it matters

It is easy to say that "being happy" keeps you young, but this study suggests the kind of well-being matters. Feeling connected to and valued by a community kept its link with a slower pace of aging after health and habits were accounted for, while life satisfaction and purpose did not. The study also shows that such links can be seen with an ordinary brain scan, which opens the door to many existing brain-imaging studies that have no blood samples. Whether building a sense of belonging actually slows aging would need long-term studies and trials, for example of volunteering programmes, as the authors suggest.