Y-BOCS

The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) is a 10-item clinician-administered rating scale considered the gold standard for measuring the severity of obsessive-compulsive disorder symptoms. Five items assess obsessions and five assess compulsions, each rated 0–4 on dimensions of time occupied, interference, distress, resistance, and degree of control. Total scores range from 0 to 40. The Y-BOCS is the primary endpoint in psilocybin-for-OCD research, including the pioneering study by Francisco Moreno at the University of Arizona (2006) and ongoing trials at Yale University. Those studies demonstrated significant acute reductions in Y-BOCS scores following psilocybin administration. A 35% or greater reduction from baseline is typically considered a clinically meaningful response. The Y-BOCS has excellent interrater reliability (ICC > 0.90) and is sensitive to treatment-related change.