Do first-line treatments for obsessive-compulsive disorder impact brain structure and function? A systematic review.

OBJECTIVE

To examine studies investigating structural and functional brain changes in individuals receiving first-line treatments for obsessive-compulsive disorder (OCD), including cognitive-behavioral therapy (CBT) or selective serotonin reuptake inhibitors (SSRIs).

METHODS

This systematic review analyzed 26 neuroimaging studies involving 958 participants with OCD, using magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), resting-state functional magnetic resonance imaging (rsfMRI), and diffusion tensor imaging (DWI) to examine brain volume, cortical thickness, functional connectivity, and white-matter integrity before and after treatment.

RESULTS

Both CBT and SSRI were associated with structural and functional brain changes in distinct neural circuits. CBT was associated with increased activation within the frontoparietal network, enhanced white-matter integrity in frontal and temporal regions, and reduced connectivity between emotional processing areas, such as the amygdala and the ventromedial prefrontal cortex. SSRIs, in contrast, were associated with increased left putamen volume, decreased activity in the insula and middle temporal gyrus, and modified white-matter properties within the striatum and midbrain.

CONCLUSION

Both CBT and SSRIs modulate brain networks involved in executive control, emotion regulation, and sensorimotor integration, suggesting complementary neuroplastic effects and potential biomarkers of treatment response in OCD.