Even 1,000 to 2,000 more daily steps were linked to better adolescent mental health and brain structure in an observational study, with no plateau across measured activity levels.
Walking to school or chasing a ball around a park adds to adolescents’ daily movement in ways that may be connected to their mental health a year later. In a study tracking thousands of participants in the United States, researchers found fewer mental health symptoms among those who took more steps, using wearable devices to capture activity that most previous research has measured through questionnaires.
Researchers at King’s College London’s Institute of Psychiatry, Psychology & Neuroscience, working with the University of Massachusetts Amherst, followed 5,515 adolescents enrolled in the largest long-term study of brain development and child health in the United States. Known as the Adolescent Brain Cognitive Development Study, the project operates across 21 sites.
Fitbit devices recorded the participants’ steps for three weeks when they were around 11 to 12 years old, providing an objective measure of daily activity. This approach has been suggested to capture habitual movement more reliably than asking participants to report it themselves.
A year later, researchers assessed the adolescents’ mental health using the Child Behavior Checklist, a widely used questionnaire completed by the participants and their parents. They compared its measures of anxiety, low mood, and behavioral problems with the earlier step counts to examine how everyday movement related to later symptoms.
More steps, fewer mental health symptoms
Adolescents taking fewer than 5,000 steps a day had the most mental health symptoms. Those averaging around 8,000 had fewer, while those reaching 12,000 or more had the fewest. Higher step counts were not associated with better performance at school, however, suggesting that the pattern did not extend to every outcome the researchers examined.
Dr. Divyangana Rakesh, Senior Lecturer in Neuroscience and Psychology at King’s College London and senior author of the study, said: “This study gives us some of the clearest evidence yet that even an everyday, low-cost, accessible measures of physical activity like daily step count is tied to how adolescent brains and mental health develop. What’s striking is that we don’t see this benefit leveling off in the observed range, even among the most active young people in our sample.”
Thicker brain tissue offers a clue
Participants with the highest step counts also had slightly thicker brain tissue in two areas involved in movement and emotion regulation. These small differences helped account for part of the association between greater activity and better mental health, giving researchers a possible biological connection to investigate. Qingyang Li, the study’s lead author, said: “We’re starting to understand parts of the brain that might be involved in the link between daily steps and young people’s mental health. It’s preliminary, but it gives us a clearer idea of where to look next.”
Researchers accounted for the adolescents’ earlier mental health problems, and the association with step counts remained. They still could not rule out the possibility that those with fewer symptoms were more active to begin with. Following participants over time revealed a relationship, but the observational study could not establish that walking more directly improved their mental health.
Dr. Amanda Paluch, Associate Professor of Kinesiology at the University of Massachusetts Amherst, said: “Adolescence is a key period for brain development and mental health, so it’s encouraging to see that physical activity’s benefits extend to both. It is not an all-or-nothing situation. Adolescents don’t need to be elite athletes to benefit. 1,000 to 2,000 higher daily step increments, from any starting point, was associated with better brain structure and mental health outcomes, and that beneficial association keeps building from there.”
Few adolescents in the sample reached extremely high daily step counts, leaving the researchers unable to determine whether the association continues beyond the activity levels they measured. The absence of a plateau within the observed range does not establish that progressively higher counts would remain linked to better outcomes indefinitely.
Paluch brought the findings back to the walk to school and other movement that can fit into an adolescent’s day: “The goal is finding realistic, sustainable ways to move more, through everyday opportunities like walking to school, active play, and activities kids actually enjoy, so these benefits are accessible wherever an adolescent is starting from.”
Reference: “Physical Activity and Adolescent Brain Structure, Mental Health, and Academic Outcomes” by Qingyang Li, Amanda Paluch and Divyangana Rakesh, 1 October 2026, JAMA Network Open.
DOI: 10.1001/jamanetworkopen.2026.36973
Dr Rakesh acknowledges support from a Young Investigator Grant from the Brain & Behaviour Research Foundation (32908), a New Investigator Research Grant from the UK Research and Innovation Medical Research Council (MR/Z506667/1), and the Canadian Institute for Advanced Research Global Scholars Program.
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