Exploring psychophysiological indices of disruptive behavior disorder and their subtypes of aggression

BACKGROUND Psychophysiological measures of arousal are often considered as potential biomarkers for disruptive behavior disorder (DBD). Nevertheless, the evidence is mixed, possibly reflecting the heterogeneity of DBD and different subtypes of aggression. Additionally, arousal measures of the central nervous system (e.g. electroencephalogram: EEG) are underrepresented compared to peripheral ones (heart rate: HR; skin conductance: SC). METHODS We recorded HR, SC, and EEG (frequency band power at three electrodes Fz, Cz, Pz) in 49 participants with DBD, and 15 typically developing peers during two resting state and an emotional task condition. Group differences were assessed by a repeated measure ANOVA and regression analyses were applied to evaluate subtype-specific patterns. RESULTS Our results showed higher mean HR activity in DBD participants, which was however driven by medicated participants and no significant group differences were found for SC. Interestingly, a significant group x frequency band interaction emerged for the EEG. DBD youth showed lower alpha activity. Regression analyses showed that higher theta and lower alpha band activity were related to more general aggression scores and higher delta and lower beta activity predicted proactive aggression. CONCLUSIONS The lack of robust and significant differences for peripheral measurements (HR and SC) fits with previous mixed findings for externalizing disorders. Our results suggest that EEG measurements might be more sensitive to detect group differences and higher delta and lower beta activity might represent an index of a proactive subtype of aggression.