Clinical and neuroimaging correlates of cardiorespiratory fitness in adolescents with bipolar disorder

Introduction Cardiovascular disease (CVD) is exceedingly prevalent, and occurs prematurely in individuals with bipolar disorder (BD). Cardiorespiratory fitness (CRF), arguably the most important modifiable CVD risk factor, is also associated with brain structure and function. There is a gap in knowledge regarding CRF in BD, particularly in relation to brain structure. Methods Adolescents with BD (n = 54) and healthy controls (HC; n = 53) completed semi‐structured diagnostic interviews, self‐report questionnaires, and 20 minutes of cardiorespiratory exercise at 60‐80% of estimated maximum heart rate (HR) on a bicycle ergometer. Average power (watts/kg) within this HR range served as a previously validated proxy for CRF. Brain magnetic resonance imaging (MRI) structural analysis was done using FreeSurfer. Analyses controlled for age and sex. Results CRF was significantly lower in BD vs HC (0.91 ± 0.32 vs 1.01 ± 0.30, p = 0.03, F = 4.66, df=1, η2=0.04). Within BD, greater depression symptoms were associated with lower CRF (P = .02), and greater physical activity (PA) was associated with greater CRF (P BD; P = .03) and sex (M > F; P