Sex differences in adolescent ADHD: Findings from concurrent EEG and EDA

Objective: Attention Deficit Hyperactivity Disorder (ADHD) occurs more frequently in male children and adolescents than in females, with a ratio of approximately 3 to 1. We determined whether psychophysiological differences are associated with the expression of ADHD in males and females, using simultaneously recorded electroencephalography (EEG) and electrodermal activity (EDA). Methods: Quantitative EEG and EDA measures were acquired simultaneously and continuously (2 min) during an eyes closed resting condition for 70 ADHD adolescents (48 males, 22 females) and their age- and sex-matched controls. Results: Males and females with ADHD were differentiated by both EEG theta activity and EDA. ADHD males showed increased theta (widespread), whereas ADHD females showed a localised frontal enhancement of theta with reduced rate of EDA decrement. These sex differences were unrelated to ADHD subtype. Conclusions: These findings suggest that different psychophysiological processes may underlie ADHD in each sex. The profile of theta enhancement in ADHD males is consistent with a developmental deviation model of ADHD, whereas ADHD in females may be better understood within an arousal model, which emphasizes both central and autonomic function. Significance: These findings highlight the potential for concurrent EDA measures to inform EEG studies of ADHD, particularly in regard to sex differences.