Psychiatric Comorbidities in Children and Adolescents with High-Functioning Autism Spectrum Disorder: A Study on Prevalence, Distribution and Clinical Features in an Italian Sample

This study investigated the prevalence and distribution of psychiatric comorbidities in a group of 472 children and adolescents with ASD aged 3–18 years. We examined differences in age, sex, IQ, adaptive skills, and ASD symptom severity by comparing participants with ASD (ASD group) with participants with ASD and a psychiatric disorder (ASD/PSY group). Overall, 32.2% of participants had a comorbid psychiatric condition. Attention deficit/hyperactivity disorder (ADHD) was the most frequent diagnosis among preschoolers (20.4%); among school-age children, ADHD and anxiety/obsessive-compulsive disorders were the most frequent conditions (21% and 10.6%, respectively); finally, adolescents exhibit higher prevalence of anxiety/obsessive-compulsive disorders (21.8%). The ASD/PSY group showed a higher percentage of males, they were older and showed lower adaptive skills than the group with ASD; moreover, their mothers exhibited higher stress levels than mothers of participants in the ASD group. The comparison between age groups in participants within ASD/PSY group revealed that preschoolers had lower IQ than school-age children and adolescents, and worse adaptive skills, more repetitive behaviors, and restricted interests than adolescents. This study highlights the importance of an accurate diagnosis of psychiatric comorbidities in children and adolescents with ASD, also considering individual and family impairment.