Abstract
Comorbidity and symptom overlap are common among psychiatric disorders of childhood. Consequently, differential diagnosis is often a challenge. This study addresses the diagnostic utility of the BASC-3 in differential diagnosis of autism spectrum disorders (ASD) versus ADHD using demographically similar samples of children who had undergone comprehensive diagnostic studies prior to the BASC-3 being administered. Results indicated that the BASC-3 Parent and Teacher rating scales, primarily the Atypicality, Withdrawal, Developmental Social Disorders, and Autism Probability Index scores, were both sensitive and accurate to ASD and differentiated this disorder with strong accuracy from ADHD and did so as well and in some instances better than longer assessments. The Hyperactivity and Attention Problems scales did not add to this differentiation, also pointing out the need for comprehensive assessment using omnibus scales such as BASC-3 in differential diagnosis.