Differences in clinical symptoms and hot and cold executive function in girls and boys with ADHD with and without ODD

<b>Objective:</b> Oppositional defiant disorder (ODD) frequently co-occurs with attention-deficit/hyperactivity disorder (ADHD) and may impact sex differences in clinical and executive function (EF) phenotypes of ADHD. This study examines whether clinical symptoms and "hot" and "cold" EF task performance differs among children with ADHD with and without ODD relative to typically developing (TD) children. <b>Method:</b> Participants included 372 8-12-year-old children: 158 with ADHD without ODD (28% girls), 74 with ADHD + ODD (28% girls), and 140 TD (34% girls). Parent- and self-report questionnaires assessing ADHD symptoms, externalizing and internalizing problems, emotional lability, and irritability were obtained. Children completed delay discounting, go/no-go (GNG), and spatial span tasks to assess hot and cold EF. <b>Results:</b> Relative to same-sex children with ADHD, girls with ADHD + ODD showed higher inattention symptoms, whereas boys with ADHD + ODD showed higher hyperactive/impulsive symptoms. Emotional lability and irritability were higher in children with ADHD + ODD than ADHD, regardless of sex. For EF tasks, greater delay discounting was observed in girls with ADHD + ODD compared to TD girls, whereas boys with ADHD only showed poorer visual-spatial working memory compared to boys with ADHD + ODD. Boys and girls with ADHD (regardless of ODD) showed higher GNG reaction time variability than TD children, whereas only boys with ADHD (regardless of ODD) made more inhibition errors than TD boys. <b>Conclusions:</b> While symptom measures consistently differentiated ADHD from ADHD + ODD groups regardless of sex, hot and cool EF differences varied across measures and by sex, demonstrating their value in understanding sex differences in youth with ADHD with and without co-occurring ODD.