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Dimensional association between ADHD traits and gray matter volume in young adults: A voxel-based morphometry study
Haruka Asaoka1, Michio Takahashi2, Kentaro Oba2
1Department of Aging Research and Geriatric Medicine, Institute of Development, Aging and Cancer Tohoku University Sendai Japan.
Aim:
Prior structural magnetic resonance imaging (MRI) studies of attention-deficit/hyperactivity disorder (ADHD) have primarily focused on clinically diagnosed samples, whereas the neuroanatomical correlates of dimensional ADHD traits in healthy young adults (aged 18-27 years) remain insufficiently characterized, and it is unclear whether neuroanatomical patterns reported in clinically diagnosed samples generalize to subclinical trait variability in young adulthood. We therefore examined whole-brain voxelwise associations between gray matter volume (GMV) and the Conners' Adult ADHD Rating Scales (CAARS) Hyperactivity/Restlessness subscale as the primary analysis, and evaluated associations with other CAARS scales on an exploratory basis, using voxel-based morphometry (VBM).
Methods:
Participants were 534 healthy young adults (304 males, 230 females; aged 18-27 years) without an ADHD diagnosis. ADHD traits were assessed using CAARS. High-resolution T1-weighted structural MRI data were acquired on a 3-Tesla scanner. GMV was analyzed using VBM implemented in SPM12. Voxelwise multiple-regression analyses were conducted, with Hyperactivity/Restlessness as the primary scale of interest and other CAARS scales examined in separate exploratory models. Statistical significance was set at p < 0.05 (cluster-level family-wise error [FWE]-corrected), using a voxelwise cluster-forming threshold of p < 0.001 (uncorrected).
Results:
GMV in the right dorsolateral prefrontal cortex (DLPFC) showed a small but statistically significant positive association with Hyperactivity/Restlessness scores (cluster-level FWE-corrected p = 0.017). No significant associations were observed for other CAARS subscales, and no significant sex-stratified effects were detected.
Conclusion:
These findings are consistent with a dimensional perspective on ADHD-related traits and suggest that interindividual differences in Hyperactivity/Restlessness may be reflected in subtle GMV variation in the right DLPFC among healthy young adults. Further multimodal and longitudinal studies are warranted to clarify developmental and mechanistic interpretations.
