Key Elements in Differentiating ADHD and Autism

ADHD and autism spectrum share several clinical features making the differential diagnosis challenging.  Both disorders show impairment in executive control (planning and carrying out complex cognitive tasks) and problems with social function.  Methods to distinguish the two are needed to aid clinicians and parents in obtaining the correct diagnosis and beginning appropriate treatment.

Buhler  and colleagues have recently published a study that examines the psychological qualities of inhibitory control and theory of mind as differential qualities.  The key elements of the design of their study include:

Subjects: Three groups--one group diagnosed with autism spectrum disorder from a German special ASD clinic.  A second group of children diagnosed with ADHD.  A third group consisted of children with both a ASD diagnosis and an ADHD diagnosis.

Neuropsychological testing included a test of attention performance (Test Battery for Attention Performance-TAP) and theory of mind (Facial Emotion Matching-FEM) and the Social Attribution Task (SAT).

Statisitical Analysis: Discriminant function analysis was completed to determine the combination of testing scores that separated the diagnostic groups.

The authors found that combining commission errors from the TAP and the eye-mistakes from the FEM provided moderate classification among younger children (positive predictive value for ASD 65% and for ADHD 79%).  The older children (over 10 years old) were discriminated by a combination of commission errors on the TAP and the reaction time on the FEM.  The positive predictive values were somewhat lower for the older children--63% for ASD and 51% for the ADHD group.

The authors concluded: "..a specification of the existing categories of ASH and ADHD interms of the parameter inhibitory control and by adopting a developmental prospectives with theory of mind, allows to differentiate between the disorders."

Combined neuropsychological testing and brain imaging may provide a better research strategy to distinguish between these two childhood onset disorders. 

Photo of Juno Beach Florida Sunrise Courtesy of Yates Photography

Bühler E, Bachmann C, Goyert H, Heinzel-Gutenbrunner M, & Kamp-Becker I (2011). Differential Diagnosis of Autism Spectrum Disorder and Attention Deficit Hyperactivity Disorder by Means of Inhibitory Control and 'Theory of Mind' Journal of autism and developmental disorders PMID: 21373957