The difference between autism and ADHD is in the eye of the cognitive task?

A body of literature has indicated shared characteristics of children with autism spectrum disorders (ASDs) and Attention Deficit Hyperactivity Disorder (ADHD). The purpose of the current study was to demonstrate how different cognitive-attentional tasks may distinguish between children with ASDs and ADHD dependent upon the cognitive-attentional task. Multivariate analyses of covariance (MANCOVAs) were performed to determine whether the Leiter-R sustained attention subscale task and a rapid letter naming task distinguished between children with ADHD and ASDs, respectively in Study 1 and Study 2. Leiter-R sustained attention subscale task scores did not distinguish between children with ADHD and ASDs. Rapid letter naming performance, however, did appear to distinguish between children with ADHD and ASDs. Different cognitive-attentional tasks may distinguish differently between children with ADHD and ASDs.