Neural processing of working memory in adults with ADHD in a visuospatial change detection task with distractors

PeerJ. 2018 Sep 18:6:e5601. doi: 10.7717/peerj.5601. eCollection 2018.

Abstract

Individuals with Attention-Deficit Hyperactivity Disorder (ADHD) are often characterized by deficits in working memory (WM), which manifest in academic, professional, and mental health difficulties. To better understand the underlying mechanisms of these presumed WM deficits, we compared adults with ADHD to their peers on behavioral and neural indices of WM. We used a visuospatial change detection task with distractors which was designed to assess the brain's ability to effectively filter out distractors from WM, in addition to testing for effects of WM load. Twenty-seven unmedicated adults with ADHD were compared to 27 matched peers on event-related potential (ERP) measures of WM, i.e., the contralateral delay activity (CDA). Despite severe impairments in everyday life functioning, findings showed no difference in deficits in behavioral tests of working memory for adults with ADHD compared to their peers. Interestingly, there were differences in neural activity between individuals with ADHD and their peers showing that the CDA of individuals with ADHD did not distinguish between high, distractor, and low memory load conditions. These data suggest, in the face of comparable behavioral performance, a difference in neural processing efficiency, wherein the brains of individuals with ADHD may not be as selective in the allocation of neural resources to perform a WM task.

Keywords: ADHD; Attention; CDA; EEG; Working memory.

Grants and funding

This research was supported financially by a CIHR Operating Grant (# 245899, Tannock & Lewis) and by the Canada Research Chair program (RT). Finally, the current project would not have been possible without the support of the College of Education and Human Development at Texas A&M University which provided the first author a scholarship allowing him to pursue this endeavor. There was no additional external or internal funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.