A study of more than 5,500 US adolescents found that those who walked further tended to report better mental health a year later and showed small differences in brain structure.
Parents and carers looking at teenagers today may feel a familiar unease: more anxiety, less movement, poorer sleep and a growing list of health problems once associated with middle age. Yet a new study in JAMA Network Open suggests a simple habit may help tilt the odds in a healthier direction. The research found that teenagers who walked more each day tended to have better mental health a year later, along with small but measurable differences in brain structure.
That finding lands against a troubling wider backdrop. The CDC’s 2025 Youth Risk Behavior Survey found that 33% of US high school students said they had felt persistently sad or hopeless during the previous year, according to the agency’s Youth Health in Focus report. While that was an improvement from the 2021 peak and from 2023, the burden remains heavy, especially for girls, 43% of whom reported persistent sadness compared with 24% of boys. The same CDC reporting showed that 14% of students seriously considered suicide and 6% attempted it in 2025, both down from 2023 but still deeply concerning. A September 2026 CDC release said the latest figures point to encouraging progress, but stressed that the overall picture still demands attention.
The mental health data sit alongside equally worrying physical trends. National survey data show rising obesity in children and teenagers, while blood sugar problems are becoming more common at younger ages. Sleep is also short: only about a quarter of high school students are getting at least eight hours on a typical school night. At the same time, physical activity remains low. The CDC reported that only 25% of high school students were active for at least 60 minutes a day, and just 16% met both aerobic and muscle-strengthening guidelines. Girls were less active than boys, and students in rural areas were generally more active than those in urban settings.
The new JAMA Network Open study adds a useful piece to that puzzle. Researchers tracked 5,515 adolescents in the Adolescent Brain Cognitive Development Study, the largest long-term study of brain development in the United States, and used wrist-worn Fitbits to measure their steps over three weeks. On average, the young people took about 9,600 steps a day. Those who logged more steps had fewer symptoms of anxiety, depression, attention problems and behavioural issues one year later, even after the researchers adjusted for earlier mental health, family income, parental education, neighbourhood disadvantage, access to green space and body weight.
The benefit did not appear to flatten out. Compared with teenagers taking fewer than 5,000 steps a day, mental health scores improved steadily across higher step ranges, with the strongest results among those taking 12,000 steps or more. The study also found small structural differences in the brain: more active adolescents tended to have slightly thicker cortex in areas involved in movement, emotion regulation and conflict control. The authors said the relationship between more steps and better mental health was partly explained by one of those regions, the paracentral lobule, although they cautioned that longer follow-up is needed to know whether movement is slowing the normal thinning that occurs during adolescence.
The study did not show that walking causes better mental health, and it did not find a clear link between total step count and grades. Still, the results fit a broader research pattern. A 2026 umbrella review in the Journal of the American Academy of Child and Adolescent Psychiatry, pulling together 375 randomised trials, found that physical activity reduced symptoms of depression in children and teenagers. Separate trials have also shown benefits for insulin sensitivity and liver fat in adolescents with obesity, suggesting that the metabolic rewards of movement begin quickly, well before weight changes appear.
For parents, the message is practical rather than abstract. Physical activity is not a substitute for therapy or medication when a teenager needs them, but it is a low-cost habit with wide potential benefits. The federal guideline is 60 minutes of moderate-to-vigorous activity a day for people aged 6 to 17. Families can start small: more walking, less sitting, a walk after dinner, a bike ride when it is safe, a team sport, dance, swimming or simple bodyweight exercises. The key is consistency, not perfection. The newest evidence suggests that with teenagers, every extra step may count.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
