A Review of Attention-Deficit/Hyperactivity Disorder Measures for Children with Autism Spectrum Disorder

Background:  The new DSM-5 diagnostic criteria for Autism Spectrum Disorder (ASD) permit diagnosis of Attention-Deficit/Hyperactivity Disorder (ADHD) in individuals with ASD.  Considerable phenotypic overlap exists between ASD and ADHD.  It has been reported that approximately 30% of children with ADHD also meet the criteria for ASD, while approximately 50% of children with ASD meet the criteria for ADHD.  Children with comorbid ASD and ADHD tend to experience more significant impairment in psychosocial, adaptive, and cognitive functioning; motor skills and executive control than children with a single diagnosis.  Attentional difficulties, social impairment, and challenging behaviours are common in ADHD and ASD.  Both disorders are more prevalent in boys than girls.  However, social difficulties common in individuals with ADHD, such as peer rejection, are qualitatively different from the social disengagement and communication deficits present in individuals with ASD.  Similar behaviours may have different antecedents; for example, tantrums may be due to intolerance to changes in routine in ASD, and to poor self-control or impulsivity in ADHD.

Objectives:  It is essential that clinicians distinguish and identify commonalities between symptoms of ASD and ADHD.  There is a need to delineate which ADHD measures are valid for ASD assessment.  Thus, the purpose here was to review the literature on measures assessing ADHD symptoms in children with autism.

Methods:  Peer-reviewed articles on ADHD assessment in children with ASD were retrieved using PsycInfo, PsycCritiques, PsycArticles, and PsycTests databases.  Additional articles were identified from references in search-retrieved papers.  Articles included in this review (a) utilized a sample of children with ASD; (b) used ADHD measures or interviews; and (c) reported psychometric properties of the instruments.

Results:  Few measures have been specifically designed to assess comorbid ADHD in a population of children with ASD.  The Hyperactivity and Attention Problems subscale scores from the Behavioral Assessment System for Children – Second Edition (BASC-2) have been used on both clinical and nonclinical samples of children with ASD.  Normative data and clinical profiles for individuals (ages 2:0 through 21:11) with ASD are available for the BASC-2 parent and teacher report forms.  Authors of the BASC-2 have reported high internal consistency, test-retest reliability, inter-rater reliability, and adequate concurrent validity.  The Autism Spectrum Disorders – Comorbidity for Children (ASD-CC) is a measure of comorbid psychopathology for those with ASD.  It is a 49-item rating scale assessing emotional difficulties, such as ADHD, which co-occur with ASD.  The ASD-CC differentiates symptoms within the average range for children and adolescents with ASD from clinically significant symptoms.  Developers of the ASD-CC have reported moderate inter-rater reliability, test-retest reliability, and validity.  The Autism Comorbidity Interview – Present and Lifetime Version (ACI-PL) is a parent interview to identify comorbid psychopathology, such as ADHD, in ASD.   The ACI-PL distinguishes between attention to special interests and general attention.

Conclusions:  Clinicians need to address the phenotypic overlap between ASD and ADHD.  A comprehensive assessment of ADHD when ASD is suspected is crucial, as treatment implications differ considerably between the two.  Future research should examine treatment methods for individuals with co-occurring ASD and ADHD.