Cognitive Load Differentially Impacts Response Control in Girls and Boys with ADHD

Abstract

Children with attention-deficit hyperactivity disorder (ADHD) consistently show impaired response control, including deficits in response inhibition and increased intrasubject variability (ISV) compared to typically-developing (TD) children. However, significantly less research has examined factors that may influence response control in individuals with ADHD, such as task or participant characteristics. The current study extends the literature by examining the impact of increasing cognitive demands on response control in a large sample of 81children with ADHD (40 girls) and 100 TD children (47 girls), ages 8–12 years. Participants completed a simple Go/No-Go (GNG) task with minimal cognitive demands, and a complex GNG task with increased cognitive load. Results showed that increasing cognitive load differentially impacted response control (commission error rate and tau, an ex-Gaussian measure of ISV) for girls, but not boys, with ADHD compared to same-sex TD children. Specifically, a sexually dimorphic pattern emerged such that boys with ADHD demonstrated higher commission error rate and tau on both the simple and complex GNG tasks as compared to TD boys, whereas girls with ADHD did not differ from TD girls on the simple GNG task, but showed higher commission error rate and tau on the complex GNG task. These findings suggest that task complexity influences response control in children with ADHD in a sexually dimorphic manner. The findings have substantive implications for the pathophysiology of ADHD in boys versus girls with ADHD.

Reduced intrasubject variability with reinforcement in boys, but not girls, with ADHD: Associations with prefrontal anatomy

“…For example, prior studies have shown that motor control deficits are more prominent in boys than in girls with ADHD (Cole, Mostofsky, Larson, Denckla, & Mahone, 2008), whereas impairments in working memory and related EFs are present in both boys and girls with the disorder (Rucklidge, 2010). Consistent with these earlier studies, recently published findings in a large sample of girls and boys with ADHD compared to typically developing (TD) children found evidence of impaired response control in boys with ADHD across tasks with varied cognitive demand, whereas girls with ADHD only performed more poorly when working memory was necessary to guide response selection (Seymour, Mostofsky, & Rosch, 2015). In addition, a recent structural neuroimaging study found evidence of reduced cortical surface area in premotor regions in boys, but not girls, with ADHD, and more widespread surface area reductions in prefrontal regions in girls compared to boys with ADHD (Dirlikov et al, 2015).…”

“…However, motivational contingencies improved ISV among TD children despite strong baseline performance. Findings from a recent study (Seymour et al, 2015) suggest that impaired response control among girls with ADHD is only present during a task with greater executive function demands, during which working memory was necessary to guide response control, but not during a response control task with minimal cognitive demands. In contrast, boys with ADHD demonstrated elevated ISV during tasks with minimal and greater cognitive demands, as shown in a previous study (Seymour et al, 2015) and on both the standard and motivational GNG compared to TD boys in the current study.…”

“…Findings from a recent study (Seymour et al, 2015) suggest that impaired response control among girls with ADHD is only present during a task with greater executive function demands, during which working memory was necessary to guide response control, but not during a response control task with minimal cognitive demands. In contrast, boys with ADHD demonstrated elevated ISV during tasks with minimal and greater cognitive demands, as shown in a previous study (Seymour et al, 2015) and on both the standard and motivational GNG compared to TD boys in the current study. This divergent pattern of findings regarding impaired performance during the standard GNG and change in performance with motivational contingencies might suggest different underlying causes of ISV in boys and girls with ADHD.…”

“…Given the lack of studies examining ADHD-related sex differences in cognitive deficits and response to motivational contingencies, we examined whether response control, or consistent and accurate execution of a motor response as reflected in measures of response inhibition and consistency (i.e., reaction time variability), was similar among boys and girls. The specific hypotheses include: (1) boys, but not girls, with ADHD will show poorer response control relative to TD children during a standard GNG task (see Seymour et al, 2015), (2) response control will improve during a motivational GNG task for all participants with the greatest improvement in the ADHD group, possibly eliminating diagnostic differences present during the standard condition, and (3) the extent to which response control is improved during the motivational GNG will be correlated with prefrontal cortex surface area.…”

Increased Delay Discounting on a Novel Real-Time Task among Girls, but not Boys, with ADHD

“…Studies have also reported sex differences in neuropsychological functioning in children with ADHD (Hasson & Fine, 2012; O’Brien, Dowell, Mostofsky, Denckla, & Mahone, 2010; Seymour, Mostofsky, & Rosch, 2015; Wodka et al, 2008), with girls generally showing more deficits in planning and strategy mediated by prefrontal circuits, and boys showing greater impairments in more basic aspects of response control mediated by motor/ premotor circuits. Two recent studies revealed a sexually dimorphic effect of working memory demands (Seymour et al, 2015) and reinforcement (Rosch, Dirlikov, & Mostofsky, 2015) on response control. Specifically, girls with ADHD only displayed impaired response control under conditions of greater working memory demands, whereas response control was impaired among boys with ADHD regardless of working memory demands (Seymour et al, 2015).…”