Linking anterior cingulate sulcal variability to attention-deficit hyperactivity disorder behavior
Background: The anterior cingulate cortex (ACC) is consistently implicated in attention-deficit/hyperactivity disorder (ADHD). ACC variability, including its most variable structure, the paracingulate sulcus (PCGS), has been known since the late 1800s, and since then, has been linked to cognitive control, impulsivity, and psychiatric conditions comorbid with ADHD, including autism spectrum disorder and schizophrenia. Yet, the role of the PCGS in ADHD remains unexamined at the individual level. Methods: We characterized PCGS incidence, asymmetry, and morphology in 247 children and adolescents (144 ADHD: 10.9 +/- 2.73 years old, 75% male; 103 neurotypical: 12.2 +/- 3.17 years old, 50% male) from the ADHD-200 dataset. The PCGS was manually identified in FreeSurfer cortical surface reconstructions. Morphometric measures, including sulcal length, depth, and cortical thickness, were extracted and normalized to hemisphere-wide variables. Between-group analyses tested whether PCGS presence, asymmetry, and quantitative morphology differed by diagnosis, while behavioral analyses examined associations with inattention, hyperactivity-impulsivity, and cognitive measures. Age and gender were included as covariates. Results: Analyses revealed that, in both NT and ADHD individuals, there was significant leftward asymmetry in PCGS presence. Between groups, the PCGS was less likely to be present in individuals with ADHD in the left hemisphere. Leftward PCGS absence was also associated with significantly higher ADHD index and hyperactivity-impulsivity scores. Conclusions: These findings advance understanding of how early neurodevelopmental variation in cortical folding may serve as a structural intermediary between genetic liability and the behavioral expression of ADHD.