Inherited characteristics can influence the likelihood of developing depression, but genetic susceptibility does not determine every aspect of a person's mental health.

New research suggests that physical activity may help weaken the relationship between genetic vulnerability and the severity of depressive symptoms.

What the Researchers Discovered

Researchers from the University of Texas at San Antonio and collaborating institutions analyzed data from 23,517 participants in the National Institutes of Health's All of Us Research Program. Participants had genetic data available, alongside health records and physical activity measurements collected through Fitbit devices.

The average participant contributed approximately 582 days of wearable data. Researchers examined daily step counts and minutes spent in moderate-to-vigorous physical activity, providing a longer-term picture of activity patterns than a brief questionnaire could offer. To estimate inherited susceptibility to major depressive disorder, the team calculated polygenic risk scores.

These scores combine information from numerous genetic variants associated with a condition. They indicate relative genetic susceptibility rather than providing a diagnosis or predicting an individual's future with certainty. The researchers then examined how genetic risk and physical activity related to depression diagnoses and symptom severity.

Genetic Risk Does Not Tell the Whole Story

The analysis found that participants with higher polygenic risk scores were more likely to have a recorded depression diagnosis. Greater physical activity was independently associated with a lower likelihood of diagnosis. However, the relationship between genetic risk and diagnosis did not differ significantly according to physical activity levels. This distinction is important: the study did not show that exercise erased inherited susceptibility or prevented depression in every participant.

A different pattern emerged when researchers examined symptom severity. Higher genetic risk was associated with more severe symptoms, but the relationship was weaker among participants who recorded greater physical activity. The pattern appeared across different activity measurements, including daily steps and moderate-to-vigorous movement.

Why Regular Movement May Support Mental Health

Physical activity influences several processes associated with psychological well-being. Regular movement may support sleep quality, stress regulation, and the functioning of brain systems involved in mood. Activities such as walking, cycling, swimming, and dancing can also provide structure, a sense of accomplishment, and opportunities for social connection. These potential benefits may operate alongside inherited influences rather than replacing them.

Genetic susceptibility reflects the combined effects of many variants, while daily behavior and life experiences contribute additional influences on mental health. The study did not directly test which biological or psychological mechanisms explained the observed relationship. Its findings therefore offer evidence of an association, not proof that exercise directly changes the effects of genetic susceptibility.

Expert Insight

Qiliang He, the study's first author and a researcher at the University of Texas at San Antonio, explained the broader value of physical activity: “Physical activity is one of the most powerful forms of behavioral medicine, with well-established benefits for many chronic and mental health conditions, including depression.”

How Fitness Trackers Strengthened the Research

Many earlier studies relied on participants recalling how often they exercised. Such reports can be affected by memory, personal interpretation, and changes in mood. Using Fitbit records allowed researchers to assess activity over a much longer period. Repeated measurements offered a more detailed picture of everyday movement than a single assessment could provide.

Nevertheless, wearable devices have limitations. They cannot capture every form of physical activity equally well, and the amount of movement recorded does not reveal every factor affecting a person's mental health. The analysis also depended on available medical records and participant-reported information.

An analysis of more than 23,000 participants found that greater physical activity was associated with a lower likelihood of depression diagnosis and a weaker relationship between genetic risk and symptom severity. The results suggest that inherited susceptibility does not fully determine the severity of depressive symptoms.

Regular movement remains a promising component of broader mental health support, but the findings do not prove cause and effect or establish a personalized exercise prescription. Future research will help clarify how physical activity can best complement established approaches to depression prevention and care.