Examining the Overlap Between ADHD and Autism Spectrum Disorder (ASD) Using Candidate Endophenotypes of ADHD.
Objective: Recent discussions of aetiological overlap between ADHD and Autism Spectrum Disorder (ASD) require comparative studying of these disorders.


METHOD
We examined performance of ASD patients with (ASD+) and without (ASD-) comorbid ADHD, ADHD patients, and controls for selected putative endophenotypes of ADHD: Intrasubject Variability (ISV) of reaction times, working memory (WM), inhibition, and temporal processing.


RESULTS
We found that patients with ADHD or ASD+, but not ASD-, had elevated ISV across the entire task battery and temporal processing deficits, and that none of the groups were impaired in WM or inhibition. High levels of ISV and generally poor performance in ASD+ patients were only partially due to additive effects of the pure disorders.


CONCLUSION
Overall, we conclude that, within our limited but heterogeneous task battery, ISV and temporal processing deficits are most sensitive to ADHD symptomatology and that controlling for ADHD comorbidity is mandatory when assessing ISV in autism.
['Salunkhe|G|G|', 'Weissbrodt|K|K|', 'Feige|B|B|', 'Saville|C W N|CWN|', 'Berger|A|A|', 'Dundon|N M|NM|', 'Bender|S|S|', 'Smyrnis|N|N|', 'Beauducel|A|A|', 'Biscaldi|M|M|', 'Klein|C|C|']
D001289:Attention Deficit Disorder with Hyperactivity D000067877:Autism Spectrum Disorder D015897:Comorbidity D058068:Endophenotypes D006801:Humans D008570:Memory, Short-Term D011930:Reaction Time
endophenotypes intrasubject variability working memory response inhibition temporal reproduction