Parent Reported Symptoms of Attention Deficit Hyperactivity Disorder In Children with and without Autism Spectrum Disorders

Background:  

A growing number of researchers are reporting symptoms meeting DSM-IV criteria for Attention Deficit Hyperactivity Disorder (ADHD) in a significant number of children diagnosed with Autism Spectrum Disorders (ASD).  Moreover, among children with ASD, those with clinically significant ADHD symptoms have been found to be more impaired in social and adaptive functioning than those without ADHD symptoms.

Objectives:  

The goals of the current study were to investigate parent reported symptoms of ADHD in children with and without ASD enrolled in a prospective study of child development, and to examine whether there are additive effects of ADHD on the severity of symptoms associated with ASD.

Methods:  

Participants included 162 children (100 males), ages 4 - 8 years (X = 5.6, SD = 1.27),   with and without ASD enrolled in a prospective study of child development, including: a) n=102 younger siblings of children with autism; (b) n = 35 children diagnosed with ASD participating in early intervention programs; (c) n = 12 control children with no known family history of ASD and; (d) n = 13 children with specific language delay.

Parents completed the Behavior Assessment Scale for Children, second edition (BASC-2), and the Social Responsiveness Scale (SRS).  Clinicians completed the Autism Diagnostic Observation Schedule-Generic (ADOS) and the parent-interview version of the Vineland Adaptive Behavior Scale-second edition (VABS-II).

Classification of ADHD and Grouping of Participants.  Children were classified as ADHD positive (ADHD +) if they scored at or above the clinical threshold (> 70) on either the Hyperactivity or Attention Problems subscales on the BASC-2.  Children were placed into one of four diagnostic classification groups:  No ADHD or ASD; ADHD Only; ASD Only; or ASD+ADHD.

Results:  

Rates of ADHD in Children with and Without ASD.  A Chi-Square analysis revealed that a significantly higher percentage of parents of children with ASD rated their child at or above the clinical cutoff on at least one of the two ADHD subscales of the BASC-2 compared with children without ASD (29% vs 9%, respectively; X = 11.06, p = .001).  

Additive Severity of ADHD on ASD.  One-Way ANOVAs revealed significant differences in social and adaptive functioning (ps < 0.001), with the ASD+ADHD Group rated by parents as significantly more impaired in social responsiveness and adaptive functioning on the SRS and the VABS-II than the ASD Only group (post-hoc comparisons, ps < 0.05). 

Conclusions:  

The current study adds to the growing body of literature documenting an increased risk of ADHD in children with ASD.  As expected, compared with children without an ASD, parents rated a significantly higher percentage of children with ASD with clinically significant symptoms of ADHD.   Moreover, children identified with ASD and ADHD, as compared with children with ASD only, were rated by their parents as significantly more impaired in social and adaptive functioning.  Future research is needed so that specialized treatments and interventions can be designed to target impairments associated with this subgroup of children comorbid with ASD/ADHD.