Abstract
Developmental Coordination Disorder and Attention-Deficit/Hyperactivity Disorder are unique neurodevelopmental disorders with overlaps in executive functions and motor control. The conditions co-occur in up to 50% of cases, raising questions of the pathological mechanisms of DCD versus ADHD. Few studies have examined these overlaps in adults with DCD and/or ADHD. Therefore, to provide insights about executive functions and motor control between adults with DCD, ADHD, both conditions (DCD + ADHD), or typically developed controls, this study used a stop-signal task and parallel EEG measurement. We assessed executive performance via go accuracy and go reaction time, as well as motor response inhibition via stop-signal reaction time. This was complemented with analysis of event-related potentials (ERPs). Based on existing investigations of adults with DCD or ADHD, we expected (1) groups would not differ in behavioral performance on stop and go trials, but (2) differences in ERPs, particularly in components N200 (index of cognitive control) and P300 (index of attention and inhibition) would be evident. The sample included N = 50 adults with DCD (n = 12), ADHD (n = 9), DCD + ADHD (n = 7), and control participants (n = 22). We replicated that there were no between-group differences for behavioral-level executive performance and motor response inhibition. However, on a physiological level, ERP components N200 and P300 differed between groups, particularly during successful response inhibition. These ERPs reflect potential endophenotypic differences not evident in overt behavior of participants with ADHD and/or DCD. This suggests a disorder specific employment of inhibition or general executive functions in groups of adults with DCD, DCD + ADHD, ADHD, or control participants.
Highlights
Developmental Coordination Disorder (DCD) and AttentionDeficit/Hyperactivity Disorder (ADHD) are lifelong neurodevelopmental disorders known to co-occur in up to 50% of cases (Blank et al, 2019)
Participants were grouped based on their reported diagnostic history for DCD, ADHD, both conditions (DCD + ADHD), or no health conditions, and this was confirmed by self-reported symptoms
A further difference in C6 was driven by marginally significant differences between the DCD and ADHD groups (DCD: M = −2.93, SD = 2.31, ADHD: M = −1.02, SD = 0.94, p = 0.056) and ADHD and control groups (Control: M = −2.64, SD = 1.43, p = 0.076; see Figure 2)
Summary
Developmental Coordination Disorder (DCD) and AttentionDeficit/Hyperactivity Disorder (ADHD) are lifelong neurodevelopmental disorders known to co-occur in up to 50% of cases (Blank et al, 2019). Evidence for substantial symptomatic overlaps between the two disorders has been observed This includes children with DCD displaying hyperactivity (Harrowell et al, 2018), and having deficiencies in executive functions (Bernardi et al, 2015; Sartori et al, 2020) with the latter potentially persisting overtime (Bernardi et al, 2018; Wilson et al, 2020). This research gap was documented in a recent international consensus on DCD, in which the authors highlight a generally growing body of research on adult populations (Blank et al, 2019) To expand on this literature, a better understanding of the mechanisms involved in executive functions and motor skills for adults with DCD versus ADHD is pertinent
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