Attention Deficit Hyperactivity Disorder Symptoms in Young Children with Autism Spectrum Disorder

The purpose of the current study was to examine the prevalence of attention deficit hyperactivity disorder (ADHD) symptoms among young children with autism spectrum disorder (ASD), child and parent-related demographic and clinical correlates of ADHD symptoms, and the relationships between co-occurring mental health problems and ADHD symptoms. Data for this cross-sectional study came from 979 toddlers and preschoolers, ages 1.5-5 years, with ASD. The primary outcome, ADHD symptoms, was measured using the Child Behavior Check List 1.5-5 (CBCL). Additional information from the medical record included demographics, parenting stress, and Autism Diagnostic Observation Schedule Second Edition. Descriptive and bivariate (ANOVA, Chi-Square) statistics and multivariate, multinomial regression analyses were used to examine demographic and clinical differences between low, moderate, and high ADHD symptom groups, as defined by 2 ADHD-related subscales. There were 418 (43%) children in the low ADHD symptom group, 294 (30%) in the moderate ADHD symptom group, and 267 (27%) in the high ADHD symptom group. Those with high ADHD symptoms were less likely to be Black or Hispanic and less likely to have parents with a graduate-level education compared to those with low ADHD symptoms. Parenting stress and all CBCL DSM-oriented subscales were positively associated with increasing ADHD symptoms. Among young children with ASD, ADHD symptoms were highly prevalent. The presence of ADHD symptoms was associated with increasing parenting stress and greater levels of other psychopathologies. These data suggest that young children with ASD should be evaluated for ADHD, and mental health as a whole. Lay Summary We investigated attention deficit hyperactivity disorder (ADHD) symptoms in toddlers and preschoolers with autism spectrum disorder (ASD) from a large sample with diverse race and socioeconomic background. In our study, we found that ADHD symptoms are highly prevalent in young children with ASD and are associated with increasing parenting stress and greater level of other psychopathologies, both internalizing and externalizing problems.