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Child Psychiatrist /Adult Psychiatrist

Inhibition in ADHD: Girls Are Slow to Respond, Boys Have Poor Cognitive Control

Keypoint: Girls with ADHD appear to slow their response speed as a strategy to retain accurate response inhibition.

Girls with ADHD

Among children with attention-deficit/hyperactivity disorder (ADHD), response inhibition patterns vary by sex and are task-dependent, according to study results published in the Journal of Attention Disorders. Overall, boys with ADHD are more likely to display inhibition errors while girls have intact response inhibition, but slower response speeds.

The behavioral symptoms of ADHD are thought to be related to impairments in cognitive control, such as deficits in inhibition control, interference control, and attention regulation. Recent evidence suggests that boys and girls with ADHD may exhibit different types of impairments. However, girls are often underrepresented in ADHD research given the higher prevalence among boys/men, so the potential sex differences in cognitive control remain unclear.

To address this knowledge gap, researchers conducted a study to evaluate performance metrics of cognitive control across multiple tasks in both boys and girls with ADHD. The researchers recruited children aged 8 to 12 years (N=300) with a diagnosis of ADHD (n=201) and typically developing controls (n=99) in the United States. The study participants completed the go/no-go (GNG) task, stop signal task (SST), and flanker cognitive control task. The primary outcomes of interest were response speed, variability, and inhibition errors.

On average, the girls (n=58) and boys (n=143) of the ADHD cohort were aged 10.2 (SD, 1.3) and 10.4 (SD, 1.4) years while the typically developing girls (n=37) and boys (n=62) were aged 10.1 (SD, 1.4) and 10.4 (SD, 1.2) years. Among the ADHD group, 48% of girls and 57% of boys used stimulant medications. Socioeconomic status was significantly lower among the ADHD group (P =.021) and baseline inattention scores for the ADHD cohort were significantly greater among girls (P <.001) relative to boys.

For the GNG task, the researchers observed a significant effect of ADHD diagnosis for mean reaction time at go (P <.001), mean response variability in the ex-Gaussian part of reaction time (P <.001), and mean response variability in the Gaussian part of the trial (P =.014). Significant diagnosis-by-gender effects were observed for mean response variability in the Gaussian part of the trial (P =.015) and mean response speed in the Gaussian part of reaction time (P =.016). Together these differences indicate that across both groups, boys had more commission errors than girls while girls had quicker GNG response speeds than boys. Between groups, boys with ADHD had more errors than controls whereas girls with ADHD had a slower response speed than controls. Additionally, response variability was higher among children with ADHD than controls.

For the SST task, the researchers observed a main effect of diagnosis for stop signal reaction time (P <.001), mean response variability in the ex-Gaussian part of reaction time (P <.001), mean stop signal delay (P =.016), mean reaction time at go (P =.020), and commission error rate (P =.042). These differences indicated that relative to controls, patients with ADHD had higher commission error rates, with slower go response speed for girls with ADHD and shorter stop signal delay among boys with ADHD.

For the Flanker task, a main effect of diagnosis was observed for mean response variability in the Gaussian (P <.001) and ex-Gaussian (P <.001) parts of the trial and congruency effect error rate (P =.008). Overall, the patients with ADHD had greater flanker error rates than controls.

Study authors concluded, “Results of this study indicate that boys and girls with ADHD engage in distinct task-dependent strategies during inhibition tasks whereas they show similar deficits in interference control and elevated [reaction time] variability.”

Note: This article originally appeared on Psychiatry Advisor

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