Cerebral blood flow characteristics of drug-naïve attention-deficit/hyperactivity disorder with social impairment: Evidence for region-symptom specificity

Abstract

Background: Social deficits are among the most important functional impairments in attention-deficit/hyperactivity disorder (ADHD). However, the relationship between social impairment and ADHD core symptoms as well as the underlying cerebral blood flow (CBF) characteristics remain unclear.

Methods: A total of 62 ADHD subjects with social deficits (ADHD + SD), 100 ADHD subjects without social deficits (ADHD-SD) and 81 age-matched typically developing controls (TDC) were enrolled. We first examined the correlation between the Social Responsiveness Scale (SRS-1) and ADHD core symptoms (inattention, hyperactivity, and impulsion) and then explored categorical and dimensional ADHD-related regional CBF by arterial spin labeling (ASL). For the categorical analysis, a voxel-based comparison of CBF maps between the ADHD + SD, ADHD-SD, and TDC groups was performed. For the dimensional analysis, the whole-brain voxel-wise correlation between CBF and ADHD symptoms (inattention, hyperactivity/impulsivity, and total scores) was evaluated in three groups. Finally, correlations between the SRS-1 and ADHD-related regional CBF were investigated. We applied Gaussian random field (GRF) for the correction of multiple comparisons in imaging results (voxel-level P < 0.01, and cluster-level P < 0.05).

Results: The clinical characteristics analysis showed that social deficits positively correlated with ADHD core symptoms, especially in social communication and autistic mannerisms domains. In the categorical analysis, we found that CBF in the left middle/inferior temporal gyrus in ADHD groups was higher than TDCs and was negatively correlated with the social motivation scores. Moreover, in dimensional analysis, we found that CBF in the left middle frontal gyrus was negatively correlated with the inattention scores, SRS total scores and autistic mannerisms scores in ADHD + SD subjects.

Conclusion: The present study shows that inattention, hyperactivity, and impulsivity may be responsible for the occurrence of social deficits in ADHD, with autistic traits being another significant contributing factor. Additionally, CBF in the left middle/inferior temporal gyrus and the left middle frontal gyrus might represent the corresponding physiological mechanisms underlying social deficits in ADHD.

Keywords: arterial spin label; attention-deficit/hyperactivity disorder (ADHD); cerebral blood flow (CBF); comorbid; social impairment.

FIGURE 1

ADHD-related regional cerebral blood flow in the categorical analysis. (A) Differences in regional cerebral blood flow (rCBF) between ADHD with social deficit subjects (ADHD + SD), ADHD without social deficit subjects (ADHD-SD), and typically developing controls (TDC). (B) The mean rCBF in the left middle/inferior temporal (cluster = 32, and peak MNI = –57, 51, 6) in the three groups. (C) The negative correlation between the mean rCBF in the left middle/inferior temporal gyrus and social motivation scores (r = —0.275, P = 0.034) in the ADHD + SD subjects.

FIGURE 2

ADHD-related regional cerebral blood flow in the dimensional analysis. (A,B) The regional cerebral blood flow (rCBF) was negatively related to ADHD-RS-IV HI scores in the left temporal pole (r = —0.528, GRF corrected voxel P < 0.01) and positively related to ADHD-RS-IV HI scores in the right precentral gyrus (r = 0.549, GRF corrected voxel P < 0.01). (C) The rCBF value was negatively related to the ADHD-RS-IV IA scores in the left middle frontal gyrus (r = —0.521, GRF corrected voxel P < 0.01). (D) The mean rCBF in the left middle frontal gyrus was negatively correlated with SRS total scores (r = —0.321, P = 0.012) and autistic mannerisms scores (r = —0.358, P = 0.005) in the ADHD + SD subjects.