Conscientious and outgoing people had slightly “younger” blood tests in a large UK study

People who described themselves as careful and persistent, or as sociable, had blood test results that looked slightly younger than their birth certificates, according to an analysis of almost 120,000 British adults. People who scored high on neuroticism, the tendency to worry and feel upset, looked slightly older. Part of the link ran through everyday habits such as smoking, drinking and exercise. The study is large, but it measured everything once, at the same time, so it can't say what causes what.

Psychologists often describe personality with the "Big Five" traits: neuroticism (worry and emotional ups and downs), extraversion (sociability), conscientiousness (diligence and self-discipline), agreeableness (warmth and trust) and openness (curiosity). Earlier studies have tied high neuroticism to heart disease and earlier death, and high conscientiousness to longer life.

To measure aging, the team used PhenoAge, a biological age calculated from your real age and nine ordinary blood tests, including albumin, glucose, creatinine (a kidney marker), C-reactive protein (an inflammation marker) and white blood cell counts. "PhenoAge acceleration" is how many years someone's PhenoAge sits above or below what is typical for their real age. We wrote about the same measure and cancer recently (/post/2026-10-23-phenoage-cancer-disease-burden/).

What they did

• They used data from the UK Biobank, a large cohort of British volunteers. Of about 500,000 participants, 119,250 of European ancestry had all the needed information.
• Neuroticism came from a standard 12-question test. The UK Biobank had no full personality test, so the other four traits were estimated from other questions (for example about diligence, sociability or trust).
• They built a "coping behaviour" score from 0 to 6: one point each for low-risk drinking, not smoking now, enough physical activity, not overeating, no drug or medication use, and having sought professional help for mental distress.
• They compared each trait with PhenoAge acceleration, taking into account age, sex, local deprivation, heart disease, high blood pressure and diabetes. Then they asked how much of each link went through the coping score.
• Finally, they split people by a genetic score for faster PhenoAge (built from 29 DNA variants) to see whether the pattern was the same at low and high genetic risk.

What they found

• Higher neuroticism went with a slightly higher biological age.
• Higher conscientiousness, extraversion and agreeableness went with a slightly lower biological age. Conscientiousness and extraversion showed the clearest links; agreeableness a much weaker one.
• Openness was not clearly linked either way.
• Habits explained a part. The coping score accounted for about 15% of the neuroticism link, 20% of the extraversion link, 12% of the conscientiousness link and 28% of the (small) agreeableness link. Most of each link was left unexplained.
• Genes didn't change the picture much. The links for neuroticism, extraversion and conscientiousness looked similar in people with low and high genetic scores. Agreeableness was linked only in the high-score group, but a formal test found no real difference between the groups.

The effects are reported per point on each trait's own scale, so they can't be read directly as years of aging.

What to keep in mind

The authors list the limitations themselves:

• One snapshot. Personality, habits and blood tests were all measured at the same time. The study can't show that personality comes first; the "mediation" by habits is a statistical split, not a proven pathway.
• Rough measures. Only neuroticism was measured with a validated test. The other four traits were stitched together from available questions that have not been checked against real Big Five tests, so they may capture only parts of each trait.
• A mixed-bag coping score. Six yes-or-no habits can't describe the full range of how people cope with stress.
• Who was left out. About three quarters of eligible participants were dropped for missing data, and those included differed from those left out (in age, deprivation and health). A reweighted analysis gave similar results, but hidden differences may remain.
• Other explanations. Depression, sleep and stress weren't accounted for and could explain part of the links.
• Europeans only. The results may not apply to other populations.

Why it matters

The study adds to evidence that how people tend to think and behave is reflected in measures of how fast their bodies are aging, and it suggests that a share of that link may run through ordinary habits like smoking, drinking and exercise. The researchers call for studies that test each habit separately. Long-term studies that measure personality, habits and biological age repeatedly, in more diverse groups, are needed to tell whether the habits come first and whether changing them would move the needle.