Autism Spectrum Disorder and Attention-Deficit/Hyperactivity Disorder: Shared or Unique Neurocognitive Profiles?

Abstract

Attention-deficit/hyperactivity (ADHD) and autism spectrum (ASD) disorders are commonly co-occurring conditions characterized by neurocognitive impairments. Few studies have directly compared neurocognitive profiles in ADHD and ASD and fewer still have controlled for comorbidity of ADHD and ASD. All direct comparisons have been in clinic samples, leaving the question of generalizability of results unaddressed. We compared neurocognitive performance in clinically ascertained ASD (n = 261) and ADHD (n = 423) cases and controls (n = 162), 6.0–17.9 years of age. We also compared ASD (n = 190) and ADHD (n = 926) cases ascertained in the community with controls (n = 14,842) of similar age. Using the stop-signal task (SST), we measured response inhibition (stop-signal reaction time–SSRT), sustained attention (defined as reaction time variability–RTV), and reaction time (RT). We controlled for comorbidity using ADHD and ASD trait scores and categorically-defined ADHD. Compared with controls, both clinic ADHD and ASD had significantly longer SSRT and RTV than controls and did not differ from each other. ADHD traits accounted for neurocognitive impairment in ASD, but not vice versa. There were no group differences for RT. Similar patterns of neurocognitive impairment were observed in the community sample. In the largest direct comparison of ADHD and ASD to date, we found impaired response inhibition and sustained attention in both disorders. However, neurocognitive impairment in ASD was almost completely accounted for by comorbid ADHD. Results generalized in the community sample indicating that referral bias alone did not drive results. Response inhibition and sustained attention likely play a role in ADHD and ASD.

Do ASD and ADHD Have Distinct Executive Function Deficits? A Systematic Review and Meta-Analysis of Direct Comparison Studies

“…These studies do not clarify whether EFs are associated with ASD or ADHD or whether the comorbid group represents a distinct diagnostic entity (Caron & Rutter, 1991; Krakowski et al, 2021). Studies in which ADHD and ASD traits were controlled indicate that, at least response inhibition and response variability, may be more strongly associated with ADHD than with ASD traits (Karalunas et al, 2018; Schachar et al, 2022). Taken together, these results are not inferring that all children with ASD should be suspected of having ADHD because each disorder present differently clinically in other symptom areas such as in social functioning (Hours et al, 2022).…”

“…Only English articles were included, which may have excluded some international publications. We found few studies that included a comorbid group, controlled for traits of ASD and ADHD, or distinguished between ADHD subtypes precluding adequate consideration of the effect of comorbidity and subtype on EF performance (Schachar et al, 2022; Semrud-Clikeman et al, 2010).…”

Sleep problems in children with autism spectrum disorder andattention‐deficit/hyperactivity disorder: A comparative study and effects on communication skills

“…Sleep disturbances are also frequent in Attention-Deficit/Hyperactivity Disorder (ADHD) (Cortese et al, 2013), a condition with similarities to the ASD neurocognitive profile (Schachar et al, 2023), and with prevalence rates ranging from 70% to 85% (Yürümez & Kılıç, 2016). Children diagnosed with ADHD exhibit increased levels of daytime sleepiness, heightened sleep-related movements, and elevated apnea-hypopnea indices (Cortese et al, 2006).…”

Improving Functional Abilities in Children and Adolescents with Autism Spectrum Disorder Using Non-Invasive REAC Neuro Psycho Physical Optimization Treatments: A PEDI-CAT Study

“…Behavioral, mood, and psychiatric disorders are prevalent in individuals with ASD [ 2 ], which can significantly impair social, academic, and occupational functioning. Commonly observed behavioral disorders include attention-deficit/hyperactivity disorder (ADHD) [ 3 ] and obsessive-compulsive disorder (OCD), with a prevalence rate of up to 60% and 30% [ 4 ], respectively. Mood disorders, such as anxiety and depression, are also common in individuals with ASD, with a prevalence rate of up to 30% and 50%, respectively [ 5 , 6 ].…”