The effects of medication on white matter integrity in obsessive-compulsive disorder

Motivation: Studies has shown improved clinical symptoms accompanied by normalized functional connectivity after pharmacological treatment in obsessive-compulsive disorder (OCD). However, the effect of medication on structural connectivity in OCD is still unclear. Goal(s): To investigate white matter (WM) alterations in OCD and how it would be affected by pharmacological treatments. Approach: We utilized novel tractography toolbox TractSeg to reconstruct 72 tracts and investigate the fractional anisotropy (FA) alterations at tract level. Results: We observed FA reduction in tracts connecting parietal and occipital to thalamus, striatal, and frontal in OCD. Patients showed symptom improvement post-treatment, while FA in these tracts were lower compared to baseline. Impact: Although pharmacological treatment led to symptom relief in patients with OCD, this improvement was not reflected in structural connectivity. This suggests symptom alleviation in OCD may precede detectable changes in white matter microstructure following treatment.