One of the most controversial comorbidities in children with ASD is the co-occurrence of Attention Deficit Hyperactivity Disorder (ADHD). Comorbidity refers to the presence of more than one diagnosis occurring in an individual at the same time. Although there continues to a debate about ADHD comorbidity in ASD, research, practice and theoretical models suggest that comorbidity between these disorders is relevant and occurs frequently. For example, a study of comorbid psychiatric disorders in children with ASD found that approximately 71% of cases had a least one comorbid psychiatric disorder, with the most common comorbidities being social anxiety (29%), ADHD (28%), and Oppositional Defiant Disorder (28%). Although the current DSM-IV-TR hierarchical rules prohibit the concurrent diagnosis of ASD/PDD and ADHD, there is a relatively high frequency of impulsivity and inattention in children with ASD. In fact, ADHD is a relatively common initial diagnosis in young children with ASD. Some researchers suggest that there are sub-groups of children with ASD with and without ADHD symptoms.
Although comorbid psychiatric disorders in children with ASD have been studied previously, there is a need to examine the impact of co-occurring ADHD symptoms in children with ASD. A recent study published in the journal Pediatrics evaluated the frequency of co-occurring ADHD symptoms in a well-defined cohort of children with ASD and examined the relationship between ADHD symptoms and both adaptive functioning and health-related quality of life as reported by parents or other primary caregivers. The purpose of the study was to: (a) document the frequency of parent-reported ADHD symptoms in a large, geographically diverse population of children with ASD, and (b) further evaluate the differences between children with ASD and ADHD symptoms and those with few or no ADHD symptoms, with an emphasis on parent-report measures of adaptive functioning and health-related quality of life (HRQoL). Based on a review of previous studies, the researchers hypothesized that children with ASD and comorbid ADHD symptoms would have poorer HRQoL and greater impairment in adaptive functioning than children with ASD and few or no ADHD symptoms.
Method and Outcome Measures
The research was conducted as part of the activities of the Autism Speaks Autism Treatment Network (ATN), a registry collecting data on children with ASD across 14 sites in the United States and Canada. A total of 3066 children and adolescents ages 2 to 18 were eligible for participation in the study. All participants had a clinical diagnosis of ASD based on one or more diagnostic measures.
Parents completed the Child Behavior Checklist (CBCL), a parent/caregiver measure of a variety of problems exhibited during childhood. T-scores on 2 ADHD-related scales from the CBCL were used to indicate the presence of ADHD symptoms. Participants were divided into groups based on whether their parents/caregivers rated them as having clinically significant T-scores on the Attention Problem and Attention Deficit Hyperactivity Problem subscales of the CBCL. Parents were interviewed to complete the Vineland Adaptive Behavior Scales, Second Edition (VABS-II). Standard scores from VABS-II and raw scores from the parent report version of Pediatric Quality of Life Inventory (PedsQL) were then compared between groups with the use of multivariate analyses.
Results indicated that 41% of the 3,000 participants had elevated scores on one CBCL ADHD-related subscale and 19% on both subscales. Analysis of responses to the PedsQL revealed that the ASD/ADHD group had lower scores in all health-related areas measured (School Functioning, Physical Functioning, Emotional Functioning, and Social Functioning) in comparison with the group of children with ASD alone. The ASD/ADHD group also obtained statistically significantly lower scores on all adaptive behavior domains of the VABS-II (Communication, Daily Living Skills, Socialization, and Adaptive Composite) when compared with the group of children with only ASD.
Conclusion and Implications
Overall results of the study suggest greater impairment in adaptive functioning and a poorer health-related quality of life for children with ASD and clinically significant ADHD symptoms in comparison with children with ASD and fewer ADHD symptoms. This supports previous research on the negative relationship between ADHD symptoms and the development of functional life and other adaptive skills and provides further documentation regarding the relationship between comorbid symptoms and overall health-related quality of life. The results also suggest the need for additional research. For example, it would be important to determine if children with ASD that meet diagnostic criteria for ADHD differ significantly from children with ASD and ADHD symptoms in the areas of adaptive skill development and HRQoL, as well as other important areas. This question is particularly important with the impending publication of DSM-V which will remove the restriction on the comorbid ADHD diagnosis in children with ASD.
These results of the study have important implications for practitioners in health care, mental health, and educational contexts. Externalizing behavior problems, including ADHD symptoms, have been found to have a strong negative relationship with family functioning and parenting stress in children with ASD. Reducing ADHD symptoms in children with ASD, in addition to treating core symptoms, may result in greater improvement in HRQoL and adaptive functioning. Improving adaptive functioning is especially important in that a child’s level of adaptive functioning can directly influence their type of educational setting and future adjustment. Children with better adaptive skills have more opportunity to participate in grade-level activities with typical peers. Consequently, clinicians and health-care professionals should screen for symptoms of ADHD in children with ASD and, if present, consider these symptoms when developing interventions and treatment protocols.
Sikora, D. M., Vora, P., Coury, D. L., & Rosenberg, D. (2012). Attention-Deficit/Hyperactivity Disorder Symptoms, Adaptive Functioning, and Quality of Life in Children With Autism Spectrum Disorder. Pediatrics, 130, S91-97. DOI: 10.1542/peds.2012-0900G
Kuhlthau K., Orlich F., Hall T.A., et al. (2010). Health- Related Quality of Life in children with autism spectrum disorders: results from the autism treatment network. Journal of Autism and Developmental Disorders, 40(6), 721–729.
Murray M.J., (2010). Attention-deficit/hyperactivity disorder in the context of autism spectrum disorders. Current Psychiatry Reports, 12(5), 382–388.
Lee A. Wilkinson, PhD, CCBT, NCSP is author of the award-winning book, A Best Practice Guide to Assessment and Intervention for Autism and Asperger Syndrome in Schools, published by Jessica Kingsley Publishers. He is also the editor of a recent volume in the APA School Psychology Book Series, Autism Spectrum Disorder in Children and Adolescents: Evidence-Based Assessment and Intervention in Schools and author of the new book, Overcoming Anxiety and Depression on the Autism Spectrum: A Self-Help Guide Using CBT.