Working memory and behavioral inhibition in boys with ADHD: An experimental examination of competing models

ABSTRACT

Working memory (WM) and behavioral inhibition impairments have garnered significant attention as candidate core features, endophenotypes, and/or associated neurocognitive deficits of attention-deficit/hyperactivity disorder (ADHD). The relationship between ADHD-related WM and inhibition deficits remains relatively unclear, however, with inferences about the constructs’ directional relationship stemming predominantly from correlational research. The current study utilized a dual-task paradigm to experimentally examine the relationship between ADHD-related WM and behavioral inhibition deficits. A total of 31 boys (15 ADHD and 16 typically developing [TD]) aged 8–12 years completed WM (1-back and 2-back), behavioral inhibition (stop-signal task [SST]), and dual-condition (1-back/SST and 2-back/SST) experimental tasks. Children with ADHD exhibited significant, large-magnitude WM deficits for the 1-back condition but were not significantly different from children in the TD group for the 2-back, 1-back/SST, and 2-back/SST conditions. Children with ADHD also exhibited significant inhibition deficits for the SST, 1-back/SST, and 2-back/SST conditions, but the within-group effect was not significant. The findings suggest that ADHD-related stop-signal demands are upstream, or compete for, resources involved in controlled-focused attention and/or other central executive (CE), WM processes.

KEYWORDS:

• ADHD
• working memory
• behavioral inhibition
• executive function
• models

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

¹ All primary analyses were completed a second time without the 2 participants with a comorbid LD. The pattern of results did not change, so the results from the entire sample are provided.

² Three participants in the TD group had scores above 1.5 SDs on the parent ratings of ODD, conduct disorder, and/or inattention. In each case, follow-up interviews with parents indicated that the elevations reflected an isolated event and the ratings were not characteristic of the child’s typical behavior. Further, the scores were not consistent with teacher ratings, and there was no evidence of impairment.

Additional information

Funding

This work was supported by the Oklahoma Center for the Advancement of Science & Technology [grant number HR11-034].