Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are commonly comorbid, share genetic liability, and often exhibit overlapping cognitive impairments. Clarification of shared and distinct cognitive effects while considering comorbid symptoms across disorders has been lacking. In the current study, children ages 7–15 years assigned to three diagnostic groups:ADHD (n = 509), ASD (n = 97), and controls (n = 301) completed measures spanning the cognitive domains of attention/arousal, working memory, set-shifting, inhibition, and response variability. Specific processes contributing to response variability were examined using a drift diffusion model, which separately quantified drift rate (i.e., efficiency of information processing), boundary separation (i.e., speed-accuracy trade-offs), and non-decision time. Children with ADHD and ASD were impaired on attention/arousal, processing speed, working memory, and response inhibition, but did not differ from controls on measures of delayed reward discounting, set-shifting, or interference control. Overall, impairments in the ASD group were not attributable to ADHD symptoms using either continuous symptom measures or latent categorical grouping approaches. Similarly, impairments in the ADHD group were not attributable to ASD symptoms. When specific RT parameters were considered, children with ADHD and ASD shared impairments in drift rate. However, children with ASD were uniquely characterized by a wider boundary separation. Findings suggest a combination of overlapping and unique patterns of cognitive impairment for children with ASD as compared to those with ADHD, particularly when the processes underlying reaction time measures are considered separately.
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Acknowledgements This project was supported by Simons Foundation #177894 and by National Institutes of Health R01 MH096773 (Fair), R00MH091238 (Fair), R01 MH086654 (Nigg), R37 MH059105 13 (Nigg), and K23 MH108656 (Karalunas). We thank Corinne Stevens, Libby Nousen, and Andrew Bontemps for assistance with data collection and preparation. We gratefully acknowledge the participants and their caregivers, as well as the graduate students, staff, and research assistants whose remarkable dedication has made this research possible.
- Attention-deficit/hyperactivity disorder (ADHD)
- Autism spectrum disorders (ASD)
- Diffusion model
- Executive function
- Reaction time variability