Development of Physical Activity from Childhood to Adolescence in Offspring at Familial High Risk of Schizophrenia or Bipolar Disorder and Population-Based Controls: The Danish High Risk and Resilience Study.

Background: Schizophrenia and bipolar disorder are associated with elevated morbidity and premature mortality, including cardiovascular disease. This excess risk may, among other factors, relate to reduced physical activity (PA) beginning in childhood. Studying children at familial high risk of schizophrenia (FHR-SZ) or bipolar disorder (FHR-BD) may help characterize early behavioural trajectories. Study Methods: We conducted a sub study of PA within The Danish High Risk and Resilience Study VIA, a longitudinal cohort study. A total of 367 children underwent accelerometry at age 11 years, and 258 at age 15 years. Univariable analyses were performed to examine prospective associations between PA, body mass index (BMI), and motor functioning at age 11 and PA at age 15. Study Results: At age 15, adolescents at FHR-SZ and FHR-BD had fewer daily steps (Cohen's d = 0.38 and 0.43) and less continuous walking (Cohen's d = 0.37 and 0.38) than controls. From age 11 to 15, step counts and both sporadic and continuous walking declined across groups. Moderate-to-highs PA increased modestly in FHR-SZ and FHR-BD but not in controls, with no significant group interactions. Higher PA and better motor functioning at age 11 were associated with higher PA at age 15. At age 15, higher PA was associated with better functioning in adolescents and caregivers. Conclusion: Offspring at FHR-SZ and FHR-BD exhibited reduced PA at ages 11 and 15. Early assessment of PA in high-risk populations may be informative. Continued follow-up is needed to clarify the role of PA in relation to cardiovascular risk and transition to severe mental disorders.