Loss in grey matter in a small network of brain areas underpins poor reactive inhibition in Obsessive-Compulsive...

Area of Science:

• Neuroscience
• Developmental Psychology
• Psychiatry

Background:

• Reactive inhibition, crucial for impulse control, shows varying correlations with symptom severity in pediatric Obsessive-Compulsive Disorder (OCD) and Tourette Syndrome (TS).
• Previous research suggests potential structural brain differences in these conditions, but their link to reactive inhibition is not fully understood.

Purpose of the Study:

• To investigate correlations between grey matter (GM) and white matter (WM) volumes and reactive inhibition, measured by stop-signal reaction time (SSRT), in pediatric patients with OCD and TS.
• To identify specific brain regions associated with altered structural volumes and their relationship to clinical symptom severity.

Main Methods:

• Structural 3T magnetic resonance imaging (MRI) scans were acquired for 9 drug-naïve pediatric OCD patients, 11 TS patients, and 12 age-matched controls.
• Participants completed a behavioral reaching version of the stop-signal task to assess reactive inhibition (SSRT).
• Between-group analyses compared GM and WM volumes, and correlations were calculated between neuroimaging measures, SSRT, and clinical scores.

Main Results:

• Tourette Syndrome patients exhibited normal behavioral inhibitory control and neuroimaging measures compared to controls.
• Obsessive-Compulsive Disorder patients displayed significant GM volume loss in five brain areas.
• GM volume in the left inferior frontal gyrus inversely correlated with SSRT; left mid-cingulate and right middle frontal gyri correlated with OCD symptom severity; left insula and right medial orbitofrontal gyri correlated with both SSRT and symptom severity.

Conclusions:

• Cortical areas with GM loss in pediatric OCD patients are implicated in the neural network supporting reactive inhibition.
• These findings highlight specific structural brain alterations in OCD related to impaired inhibitory control and symptom severity.
• Neuroimaging and behavioral data suggest distinct patterns of structural and functional deficits in pediatric OCD versus TS concerning reactive inhibition.