(PS9-C54) Heart Rate Variability in Children and Adolescents with Comorbid Anxiety and Depressive Disorders

Heart rate variability (HRV) is a measure of beat to beat temporal changes in heart rate, regulated by the parasympathetic nervous system. In adults, decreased HRV is associated with poorer emotional, behavioral, social, and cognitive wellbeing as well as increased risk of mortality. Adults with anxiety or depressive disorders have reduced HRV compared to healthy controls, and those with both diagnoses have the greatest reductions. However, far less research has investigated the relationship between HRV and mental health in children and adolescents. Particularly little research has investigated the HRV of children and adolescents with comorbid anxiety and depressive disorder diagnoses, and it is currently unclear whether comorbidity is associated with reduced HRV in young people as it is an adults. This is notable as there is a high degree of comorbidity between these diagnoses for youth. Children and adolescents with a primary anxiety disorder and a comorbid diagnosis of depression are at heightened risk and tend to have poorer outcomes and functioning than those with a single anxiety disorder diagnosis. As such, it is important to improve our understanding of the physiological presentation of this understudied population. 35 young people aged 8-17 (71.4% female, 25.7% non-white, 5.7% Hispanic) were recruited through an outpatient clinic specializing in treating anxiety and related disorders. Participants completed a diagnostic interview and self-report measures of symptoms and functional impairment. They then completed psychophysiological monitoring including baseline HRV measurement using a BIOPAC MP150 system. 97% of participants had a primary anxiety or obsessive-compulsive disorder diagnosis and 31.40% had a depressive disorder diagnosis. We found that among children with anxiety and related disorders, those with a comorbid depression diagnosis had significantly reduced HRV (M = 3.19, SD = 0.43) compared to those without (t(33) = 2.23, p  = .001). Additionally, symptoms of depression were negatively associated with HRV across all diagnoses (r =-.40, p = .02). Decreased HRV was also associated with declines in self-reported school functioning (r =.41, p = .02).These results provide support that, as in adults, comorbid depressive disorders are associated with further reductions in HRV for children with anxiety disorders. This is correlated with increased risk of functional impairment, highlighting that children and adolescents with comorbid mental health challenges are a particularly vulnerable group with unique characteristics.