Attention deficit hyperactivity disorder (ADHD) symptoms, comorbid psychopathology, behaviour problems and gastrointestinal symptoms in children and adolescents with autism spectrum disorder

Objectives:The study aims to investigate attention deficit hyperactivity disorder (ADHD) symptoms, gastrointestinal (GI) symptoms, comorbid psychopathology and behaviour problems in children and adolescents with autism spectrum disorder (ASD).Methods:Parents of 147 children and adolescents with ASD aged 6–18 years completed the Conners 3 Parent-Short Form, Gastrointestinal Symptom Inventory, Behavior Problems Inventory-Short Form and Autism Spectrum Disorder-Comorbid for Children.Results:Fifty-six per cent of children and adolescents had a comorbid diagnosis of ADHD, yet over 70% presented with clinically significant ADHD symptoms. Forty per cent of participants received a diagnosis of ADHD before ASD and 25.6% received a diagnosis of ASD first. Relationships were found between ADHD symptoms and comorbid psychopathology, GI symptoms, and behaviour problems.Conclusions:The outcomes suggest that ADHD is being underestimated as a comorbid disorder of ASD. This may have implications on treatment and interventions for children and adolescents who have a diagnosis of both ASD and ADHD.