Longitudinal patterns of autonomic nervous system responding to emotion evocation among children with conduct problems and/or depression.

Conduct disorder (CD) and depression co-occur at far greater levels than chance, despite largely separate diagnostic criteria. One potential shared mechanism of this comorbidity is emotion dysregulation, which characterizes both internalizing and externalizing disorders. Previous research demonstrates that respiratory sinus arrhythmia (RSA)-a peripheral biomarker of emotion regulation-is attenuated among children with CD, and among children with depression. However, few studies have examined biomarkers of emotion regulation as a function of heterotypic comorbidity. We evaluated longitudinal patterns of RSA and RSA reactivity to emotion evocation across three annual assessments among 207 children diagnosed at ages 8-12 years with CD (n = 30), depression (n = 28), comorbid CD and depression (n = 80), or no psychiatric condition (n = 69). Using continuous symptom counts as predictors, Depression × CD interactions were observed for both Time 1 resting RSA and Time 1 RSA reactivity. CD, depression, and their interaction were all associated with low resting RSA at Time 1. In addition, concurrently elevated CD and depression scores predicted the greatest RSA reactivity to emotion evocation. Psychopathology scores were unrelated to developmental changes in RSA and RSA reactivity over time.