Randomized Controlled Trial of the Effects of High-Dose Ondansetron on Clinical Symptoms and Brain Connectivity in Obsessive-Compulsive and Tic Disorders

There was no effect of high-dose ondansetron on SP. However, when used as an augmentation to SRIs, ondansetron reduced overall OCD severity, which may be related to changes in the "hubness" of the sensorimotor cortex. Ondansetron's ability to modulate brainstem connectivity may underlie its variable effectiveness in reducing SP.