A pivotal study published in Neuropsychopharmacology presents the first randomized, controlled crossover trial demonstrating that a single dose of ketamine can have rapid anti-obsessional effects in adults with obsessive-compulsive disorder (OCD). This groundbreaking research, involving 15 drug-free participants with near-constant obsessions, shows that ketamine, a non-competitive N-methyl-D-aspartate (NMDA) glutamate receptor antagonist, can provide significant improvement in OCD symptoms. The trial used a double-blind, placebo-controlled design, where participants received infusions of both saline and ketamine (0.5 mg/kg). Results revealed a notable reduction in OCD symptoms during and after ketamine infusion, with half of the participants meeting criteria for treatment response a week post-infusion, marking a significant advancement in OCD treatment research.