A bracelet that counts steps, health data, then a very human question: when depression also seems to be part of a family vulnerability, can moving more still change anything? A study published in Nature Mental Health explores this link between physical activity, genetic risk and depression.
The useful answer can be summarized in a few words: in people with major depressive disorder and a higher polygenic risk,
greater physical activity was associated with less severe symptoms. But the study does not prove that exercise directly treats depression, nor that it erases a genetic risk.
What does this American study really show?
The study is based on the American program All of Us. It includes 23,517 participants aged 18 to 92with an average age of around 56 years, of which 67.2% are women. Their physical activity was estimated from Fitbit data, with an average follow-up duration of 582 days. This point is important: the researchers did not limit themselves to asking the volunteers whether they thought they were moving a lot or a little.
Genetic risk was not assessed as an individual clinical test that could be requested in a consultation. It was a polygenic risk scorecalculated from whole genome sequencing data. Diagnosis of major depressive disorder combined information from electronic medical records and self-reported diagnoses; the severity of symptoms was also taken from medical records.
This study specifically aimed to understand whether the link between physical activity and depressive symptoms varies according to genetic vulnerability.
Does genetic risk change the message?
The reported results are in the expected direction on a first point: a higher polygenic risk score was associated with a greater probability of having a major depressive disorder. For its part, higher physical activity was associated with a lower risk of depression. On the other hand, the researchers did not find a significant interaction between physical activity and genetic score for the appearance of the diagnosis of depression.
The most interesting nuance therefore concerns people already affected by major depressive disorder. In this group, those who had a higher polygenic risk and who moved more had less severe symptoms. The association was found with several activity measures, including daily steps and moderate to vigorous activity. But
no universal threshold of steps or minutes cannot be derived from these elements alone.
What can we learn from it when we live in France?
For a patient, this study does not change the basis of care. Depression remains an illness that needs to be identified, assessed and monitored. The High Authority for Health reminds that the characterized depressive episode requires appropriate care, particularly as a first resort, with psychotherapy and/or drug treatment depending on the situation. Health Insurance also emphasizes the importance of monitoring and moderate and regular physical activity when possible.
The point to remember is therefore not “do sports instead of consulting”. It is rather that the movement can be part of a global strategy, adjusted to the state of the person. Walking, daily activities, supervised sport or gentle exercises: the right format depends on fatigue, desire, symptoms, treatments and current capacities. To better recognize the symptoms of depression, the advice of a doctor remains essential.
Caution is all the more necessary as this cohort is American and made up of people with Fitbit data, which does not necessarily reflect the entire French population. The results are part of a broader body of work on physical activity and depression prevention, but they should not be transformed into an injunction. When getting up, going out or walking already seems impossible, the goal must remain realistic, supported and not guilt-inducing.