Summary: A long-term, population-based study indicates that adolescents who maintain or increase their physical activity from mid- to late adolescence are less likely to develop symptoms of depression. The Trondheim Early Secure Study tracked 873 individuals from age 6 to 18, using wrist-worn accelerometers to measure activity and structured clinical interviews to assess depressive symptoms.
The study found the most robust protective associations between ages 14 and 18. Higher overall activity—especially moderate-to-vigorous physical activity—was linked with fewer depressive symptoms during this period. The analysis also revealed a reciprocal pattern: youths who experienced elevated depressive symptoms between ages 10 and 16 tended to reduce their physical activity later on, suggesting a bidirectional relationship between physical activity and mental health.
Key facts
- Protective during late adolescence: Increases in physical activity between roughly 14 and 18 years were associated with a lower risk of developing depressive symptoms.
- Bidirectional relationship: Higher depressive symptoms in early adolescence predicted declines in physical activity in subsequent years.
- Sedentary time: Time spent sedentary showed no clear within-person association with changes in depressive symptoms.
Source: NTNU
“Young people who are less physically active over time have an increased risk of developing symptoms of depression,” says Professor Silje Steinsbekk of the Department of Psychology at the Norwegian University of Science and Technology (NTNU).
According to Steinsbekk, “The protective effect was most evident for the 14–16 and 16–18 age intervals. Both total daily activity and the share that is more intense seem particularly important for protecting mental health during these years.” The study’s results are published in the Journal of the American Academy of Child & Adolescent Psychiatry.
Large cohort followed across childhood and adolescence
The Trondheim Early Secure Study followed a sizable birth cohort with repeated measurements every two years. Physical activity was objectively recorded using accelerometers worn for seven consecutive days at each assessment. Mental health was evaluated via semi-structured clinical interviews, enabling detailed symptom-level tracking across development.
This analysis drew on data from 873 participants and seven assessment waves at ages 6, 8, 10, 12, 14, 16, and 18. In addition to activity and depressive symptoms, the researchers considered potential mediators including athletic self-esteem, body image, and organized sports participation.
Physical activity appears protective, especially in mid-to-late adolescence
Overall, results suggest that increasing or sustaining higher physical activity in mid-to-late adolescence is associated with a reduced likelihood of developing depressive symptoms compared with what would be expected if activity levels declined. The protective associations were not observed consistently in younger ages; the effect became most evident from age 14 onward.
The investigators also observed an inverse pattern in earlier adolescence: between ages 10–12 and 14–16, higher levels of depressive symptoms predicted subsequent decreases in both total activity and moderate-to-vigorous activity. This pattern supports the idea that mental health and physical activity influence each other over time rather than following a simple one-way causal path.
No meaningful link emerged between sedentary time and depressive symptoms, and the findings did not differ significantly by sex. The team found no strong evidence that athletic self-esteem, body image, or sports participation explained the observed within-person associations.
About this depression and exercise research news
Author: Nancy Bazilchuk
Source: NTNU
Contact: Nancy Bazilchuk – NTNU
Image: The image is credited to Neuroscience News
Original research (open access): “Symptoms of Depression, Physical Activity, and Sedentary Time: Within-Person Relations From Age 6 to 18 in a Birth Cohort” by Silje Steinsbekk et al., Journal of the American Academy of Child & Adolescent Psychiatry. DOI: 10.1016/j.jaac.2025.03.018
Abstract
Symptoms of Depression, Physical Activity, and Sedentary Time: Within-Person Relations From Age 6 to 18 in a Birth Cohort
Objective
To investigate within-person associations between objectively measured physical activity and clinically assessed symptoms of depressive disorders across childhood and adolescence.
Method
The study used seven biennial waves of data from a Norwegian birth cohort (n = 873; 53% girls) collected from ages 6 to 18. Accelerometers provided measures of total physical activity, moderate-to-vigorous physical activity (MVPA), and sedentary time. Depressive symptoms were assessed with semi-structured psychiatric interviews. Potential mediators—athletic self-esteem, body image, and sports participation—were measured by questionnaire. Random intercept cross-lagged panel models tested within-person relations and mediation.
Results
Significant within-person associations emerged from ages 14–16 and 16–18: decreases in total physical activity and MVPA predicted increases in depressive symptoms (PA: 14–16 years β = –0.08; 16–18 years β = –0.09; MVPA: 14–16 years β = –0.10; 16–18 years β = –0.07). Conversely, higher depressive symptoms predicted reduced physical activity from ages 10–12 and 14–16 (PA: 10–12 years β = –0.10; 14–16 years β = –0.14; MVPA: 10–12 years β = –0.10; 14–16 years β = –0.17). There was no evidence of within-person relations between sedentary time and depressive symptoms, nor significant sex differences or mediation effects.
Conclusion
Increasing physical activity levels from middle to late adolescence is associated with a lower likelihood of developing depressive symptoms than would be expected if activity declined. In this developmental window, physical activity may offer protective benefits for mental health.