Comorbidity of Attention Deficit Hyperactivity Disorder and Generalized Anxiety Disorder in children and adolescents

•Several psychiatric comorbidities are associated in children with ADHD and GAD.•Higher prevalence of psychiatric comorbidities in younger children with ADHD and GAD.•Depression is strongly associated in children with ADHD and GAD.•Depression, bipolar disorder, and ADHD family history predict the comorbid profile. The aim of the study is to explore the impact of Generalized Anxiety Disorder (GAD) comorbidity in children with Attention Deficit Hyperactivity Disorder (ADHD). Six hundred children with ADHD (mean age = 9.12 years), recruited from 2013 to 2017, participated in the study. A total of 96 (16%) children with ADHD displayed a comorbidity with GAD. ADHD + GAD were compared to 504 ADHD children without GAD in terms of cognitive and psychiatric profile, ADHD subtype and family psychiatric history. The ADHD + GAD, predominantly represented from ADHD combined (72.6%), displayed higher psychiatry comorbidity, in particular with depressive disorders, and were associated with higher rates of maternal depression, of ADHD in fathers, and bipolar disorders in second degree relatives. Moreover, younger preschool-primary school age children with ADHD + GAD showed significant higher frequency of depressive disorders versus younger preschool-primary children with ADHD without GAD. ADHD + GAD comorbidity represents a more complex clinical condition compared to ADHD without GAD, characterized by the higher frequency of multiple comorbidities and by a psychiatric family with higher rates of mood and disruptive disorders.