Neural correlates of atomoxetine improving inhibitory control and visual processing in Drug‐naïve adults with attention‐deficit/hyperactivity disorder

Abstract

Atomoxetine improves inhibitory control and visual processing in healthy volunteers and adults with attention-deficit/hyperactivity disorder (ADHD). However, little is known about the neural correlates of these two functions after chronic treatment with atomoxetine. This study aimed to use the counting Stroop task with functional magnetic resonance imaging (fMRI) and the Cambridge Neuropsychological Test Automated Battery (CANTAB) to investigate the changes related to inhibitory control and visual processing in adults with ADHD. This study is an 8-week, placebo-controlled, double-blind, randomized clinical trial of atomoxetine in 24 drug-naïve adults with ADHD. We investigated the changes of treatment with atomoxetine compared to placebo-treated counterparts using the counting Stroop fMRI and two CANTAB tests: rapid visual information processing (RVP) for inhibitory control and delayed matching to sample (DMS) for visual processing. Atomoxetine decreased activations in the right inferior frontal gyrus and anterior cingulate cortex, which were correlated with the improvement in inhibitory control assessed by the RVP. Also, atomoxetine increased activation in the left precuneus, which was correlated with the improvement in the mean latency of correct responses assessed by the DMS. Moreover, anterior cingulate activation in the pre-treatment was able to predict the improvements of clinical symptoms. Treatment with atomoxetine may improve inhibitory control to suppress interference and may enhance the visual processing to process numbers. In addition, the anterior cingulate cortex might play an important role as a biological marker for the treatment effectiveness of atomoxetine. Hum Brain Mapp 38:4850-4864, 2017. © 2017 Wiley Periodicals, Inc.

Visual processing as a potential endophenotype in youths with attention‐deficit/hyperactivity disorder: A sibling study design using the counting Stroop functional MRI

“…Notably, the right IFG and ACC are thought to be involved in inhibitory control. Our previous work also showed increased activation in the right IFG and ACC during inhibitory control in youths with ADHD as compared to neurotypical youths during a counting Stroop task (Fan, Gau, & Chou, ; Fan, Chou, & Gau, ). Moreover, parietal activation is involved in attention and visual processing (Fassbender & Schweitzer, ).…”

“…In the counting Stroop task (Fan et al, ), experimental stimuli were divided into congruent, incongruent, and control conditions, with 24 trials in each condition. In the “congruent” condition, the number of words was consistent with the meaning of the word such as “one,” “two,” “three,” or “four.” In the ”incongruent” condition, the number of words was inconsistent with the meaning of the word.…”

“…Less activation within the parietal regions was found during visual processing in children with ADHD (Silk et al, ). Moreover, several studies showed robust activity in the left SPL/precuneus (BA 7) during a counting Stroop task, suggesting that ADHD was associated with impaired visual processing (Bush et al, ; Fan et al, ). Previous studies have demonstrated that changes in brain activity related to cognitive control are sensitive to a familial risk for ADHD (Durston et al, ; van Rooij et al, ).…”

“…Previous studies have shown that patients with ADHD demonstrated poorer performance of inhibitory control in the rapid visual information processing (RVP) test (Gau & Huang, ; Gau & Shang, ; Ni et al, ), and visual processing in the spatial span (SSP) test (Gau and Shang, ; Ni et al, ), as compared to neurotypical children. The counting Stroop task in the scanner can be used to evaluate the neural substrate of inhibitory control (Bush et al, ; Chou, Chia, Shang, & Gau, ; Fan et al, ) and visual processing (Chou et al, ; Fan et al, ). Furthermore, the contrast of incongruent versus congruent stimuli was associated with inhibitory control, and the contrast of the larger versus the fewer number of words was associated with visual processing in the counting Stroop (Chou et al, ; Fan et al, ).…”

“…The counting Stroop task in the scanner can be used to evaluate the neural substrate of inhibitory control (Bush et al, ; Chou, Chia, Shang, & Gau, ; Fan et al, ) and visual processing (Chou et al, ; Fan et al, ). Furthermore, the contrast of incongruent versus congruent stimuli was associated with inhibitory control, and the contrast of the larger versus the fewer number of words was associated with visual processing in the counting Stroop (Chou et al, ; Fan et al, ). Hence, combining the CANTAB and the counting Stroop fMRI offers a better understanding of these two processes.…”