More Daily Steps, Less Depression: What Happens in The Adolescent Brain?

A study of more than 5,500 adolescents found an association between taking more steps daily, experiencing fewer mental health issues, and having greater thickness in certain regions of the brain. This correlation grew stronger as the number of steps increased; however, the researchers emphasize that the study does not prove that walking more is the direct cause of these changes.

Adolescence is a phase marked by significant shifts in both the brain and behavior, a period, however, during which physical activity levels may decline. With more time spent in front of screens, on schoolwork, and engaged in other sedentary pursuits, many adolescents spend a large portion of their day sitting.

A new study followed over 5,500 adolescents, aged approximately 12, and uncovered an intriguing association: those who took more steps each day showed fewer mental health problems and certain differences in their brain structure. Furthermore, this relationship appeared to persist a year later.

To investigate this relationship, researchers used data from a large-scale study conducted in the United States that tracks children and adolescents throughout their development. For a period of three weeks, participants wore pedometers, small devices capable of recording the number of steps a person takes in a day.

In this way, rather than asking the adolescents how much they exercised, the researchers obtained an objective measure of their daily physical activity. The participants also underwent mental health and academic performance assessments, as well as brain imaging scans, which allowed for the observation of structural characteristics of the brain.

The researchers then compared the average number of steps taken per day with various outcomes. For instance, they examined whether adolescents who walked more exhibited fewer mental health-related symptoms. They also analyzed "cortical thickness", the thickness of the brain's outermost layer, which is composed primarily of nerve cells.

This layer, known as the cerebral cortex, is involved in functions such as thinking, perception, planning, and behavioral control. Researchers found an association between a higher number of steps and a slightly thicker cortex in two brain regions, including areas related to movement and processes involved in the regulation of emotions and behavior.

To better understand these relationships, the scientists used statistical methods that allow for the analysis of multiple factors simultaneously and the tracking of how certain characteristics relate over time. One such method is called mediation analysis.

Simply put, it examines whether a third characteristic can help explain the relationship between two others. In this case, the researchers investigated whether differences in cortical thickness might play a role in the association between the number of steps taken and mental health outcomes observed one year later.

The results indicated that greater thickness in a brain region known as the paracentral area statistically mediated part of this relationship. However, this does not necessarily mean that taking more steps caused this brain region to grow, nor does it imply that the change in the brain directly caused an improvement in mental health.

Another significant finding was the so-called dose-response effect. The adolescents were compared based on different levels of physical activity, and mental health problems decreased progressively as the number of steps increased.

The researchers did not find a clear threshold within the analyzed range at which the benefits ceased to appear. In other words, no "magic number" of steps was identified beyond which mental health would improve; rather, the results suggest a continuous relationship, in which higher levels of activity were associated with better outcomes.

However, as this is an observational study, it cannot be definitively stated that walking more necessarily causes an improvement in mental health. For instance, adolescents with better mental health might also be more active for other reasons. Even so, the findings reinforce the idea that simply accumulating more movement throughout the day may be linked to healthier brain and psychological development during adolescence.

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Physical Activity and Adolescent Brain Structure, Mental Health, and Academic Performance

Qingyang Li, Amanda Paluch, and Divyangana Rakesh

JAMA October 1, 2026 2026;9;(10):e2636973.

DOI: 10.1001/jamanetworkopen.2026.36973

Abstract: 

Urbanization and digitalization are contributing to reductions in the physical activity of adolescent individuals. Daily step count is an increasingly accessible and widely used metric for quantifying physical activity, yet little is known about how it is associated with mental health, academic performance, and brain health in adolescents.

Objective  To investigate the association of daily step count and future mental health and academic performance in adolescents, and whether differences in brain structure mediate these associations. This cohort study used data from participants in the Adolescent Brain Cognitive Development (ABCD) Study (release 5.1), a large-scale, longitudinal investigation designed to comprehensively characterize psychological and neurobiological development from late childhood to adolescence. The ABCD Study was conducted across 21 sites across the US, providing a diverse and geographically distributed sample. Participants were adolescent individuals with valid daily step count data and usable neuroimaging data collected between November 2018 to November 2020. Data were analyzed from May 2025 to August 2026. Pedometer-based measurements of average daily step count over the previous 3 weeks. Linear mixed models examined associations of daily step count with mental health, academic performance, and brain structure, and assessed how these associations varied between different step count categories. Using structural equation modeling, step-count–associated brain morphology was examined to determine whether it statistically mediated the association between physical activity and mental health, and/or academic outcomes 1 year later. Dose-response associations were also examined.

Results  This study included 5515 adolescent participants (2640 [47.9%] female; mean [SD] age 11.93 [0.65] years) using step counters. Higher step count was associated with lower total mental health problems (B [SE], −0.080 [0.015]; t = −5.497; P < .001) and greater cortical thickness in the paracentral (B [SE], 0.057 [0.016]; t = 3.621; P < .001) and rostral anterior cingulate (B[SE], 0.052 [0.016]; t = 3.319; P = .001) regions. Further analyses showed a significant dose-response association, with progressively lower mental health problems across higher step categories compared with the under 5000-step group. Mediation analyses revealed that greater paracentral thickness statistically mediated the association between higher daily step count and fewer mental health problems 1 year later. In this cohort study, higher daily step counts were associated with structural differences in the brains of adolescents, which were in turn associated with better mental outcomes prospectively. Beneficial associations for mental health appeared to accrue continuously across the observed range, with no evidence of a threshold or plateau, highlighting that every step counts and the potential value of promoting daily steps in adolescents.