Long before a psychiatric diagnosis ever appears, the body may already be signaling vulnerability. For the roughly one-in-ten people who carry familial risk for schizophrenia or bipolar disorder, reduced physical activity in childhood could be an early, measurable biomarker — and potentially a modifiable risk factor for the cardiovascular burden that disproportionately shortens lives in these populations.
Drawing on accelerometry data from the Danish High Risk and Resilience Study VIA, researchers tracked 367 children at age 11 and 258 at age 15, comparing those with a parent or two siblings diagnosed with schizophrenia (FHR-SZ) or bipolar disorder (FHR-BD) against population controls. At age 15, both high-risk groups recorded meaningfully fewer daily steps and less continuous walking than controls, with effect sizes in the small-to-moderate range (Cohen's d approximately 0.38–0.43). Critically, higher motor functioning and greater physical activity at age 11 independently predicted higher activity levels at age 15, suggesting an early developmental window with genuine prognostic value.
This finding matters beyond psychiatry. The premature mortality gap — estimated at 10–20 years shorter lifespan — seen in adults with schizophrenia and bipolar disorder is substantially cardiovascular in origin, and sedentary behavior is a primary driver. The observation that activity gaps are detectable years before typical illness onset implies that intervening in middle childhood, rather than after diagnosis, could compress that mortality gap. Methodologically, the use of objective accelerometry rather than self-report strengthens confidence in the activity differences observed. However, the cohort is entirely Danish, limiting generalizability, sample attrition between ages 11 and 15 is notable, and without a control group matched for socioeconomic factors, confounding cannot be fully excluded. This is confirmatory and incremental work, but it meaningfully advances the case for incorporating physical activity screening into routine surveillance of at-risk youth.
