Childhood aerobic fitness linked to lower depression risk decades later

A 32-year Australian study suggests endurance fitness in childhood may offer greater protection against adult depression than strength or power, particularly among girls.

A long-running Australian study suggests that children with stronger aerobic fitness may be less likely to develop depression later in life, adding to evidence that regular physical activity in youth can have benefits well beyond physical health. Researchers followed more than 1,000 children and adolescents for just over three decades and found that cardiorespiratory fitness, rather than muscular strength or explosive power, was the clearest predictor of lower adult depression risk, according to the Journal of Affective Disorders and university reporting on the work.

The study drew on the Childhood Determinants of Adult Health project, which began in 1985 and assessed children aged 7 to 15 across Australia. Participants completed a timed 1.6-kilometre run to measure endurance, along with tests of jumping ability and grip strength. More than 30 years later, when the same group was in mid-adulthood, trained evaluators used World Health Organisation interviews to identify lifetime episodes of major depression. Over an average follow-up of 32.5 years, 117 women and 73 men in the study experienced clinical depression, according to the researchers.

What stood out was the pattern of results. Faster run times in childhood were associated with a lower chance of depression in adulthood, while the other measures of fitness showed little or no clear long-term effect. The lead investigators said the findings point to a specific role for aerobic conditioning, the kind built through activities that make children “huff and puff”, rather than strength alone. Research summaries from the University of Tasmania and the study’s journal listing also noted that the association appeared stronger in girls than in boys.

That sex difference is important because depression affects women more often than men, and global activity data suggest many adolescents are still not moving enough. World Health Organisation figures cited in the coverage indicate that most teenagers fall short of recommended physical activity levels, with adolescent girls particularly inactive. The researchers said the result does not mean exercise is a cure for depression, but it does support the idea that habits formed in childhood may help shape mental health later on.

The biological explanation is plausible, though not definitive. Regular aerobic exercise is thought to support brain-derived neurotrophic factor, or BDNF, a protein involved in brain cell growth and connectivity, and may also help regulate the body’s stress response system. The authors stressed that depression is influenced by a mix of genetics, environment, trauma and biology, so fitness is only one part of a much larger picture. Even so, they argued that it is a part parents, schools and communities can actively improve.