Differences in the functional connectivity of large-scale brain networks between young adults with subclinical attention-deficit/hyperactivity and autistic traits

Abstract Background Attentional impairments are associated with attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Previous evidence suggests both commonalities and differences in the nature of attention deficits between these disorders. This study aimed to investigate the neural correlates of ADHD and ASD traits in healthy individuals, focusing on the functional connectivity (FC) of the large-scale brain networks (LSBN) subserving attentional functions. Methods The participants were 61 healthy individuals (30 males; age, 21.9 ± 1.9 years). The Adult ADHD Self-Report Scale (ASRS) and Autism-Spectrum Quotient (AQ) were administered as indicators of ADHD and ASD traits, respectively. Performance in the continuous performance test (CPT) was used as a behavioural measure of sustained attentional function. Functional magnetic resonance imaging scans were performed during the resting state (Rest) and during the auditory oddball task (Odd). Regions of interest (ROI)-to-ROI analyses (FDR < 0.05) were performed to examine the relationship between FCs and psychological measures. The networks of interest were the default mode (DMN), frontal-parietal (FPN), and salience (SN) networks, as these are critical for cognitive processing (including attentional processing). Results ASRS scores, but not the AQ scores, were correlated with less frequent commission errors and shorter reaction times in the CPT. During Odd, ASRS and AQ scores were positively correlated with FC values within the DMN and FPN, respectively. The ASRS and AQ scores were positively and negatively correlated with FC values between the FPN and SN, respectively. During Rest, AQ scores were negatively and positively correlated with FC values within the SN and those between the DMN and SN, respectively. Limitations: Our sample size was relatively low, we used only the CPT to assess attentional function, and we did not examine continuity from subclinical to clinical individuals in their neural substrates. Conclusions A better performance in the CPT by individuals with subclinical ADHD traits suggests the positive effects of these traits on sustained attention. Differential associations between LSBN FCs and ASD/ADHD traits indicate different mechanisms of attentional processing in individuals with subclinical ADHD or ASD traits. This corroborates the notion of differences in sustained and selective attention between clinical ADHD and ASD.