Obsessive-Compulsive Disorder (OCD):A condition marked by unwanted intrusive thoughts (obsessions) and repetitive behaviors (compulsions) to reduce anxiety. Specialists: Psychiatrists, Psychologists, Cognitive-Behavioral Therapists. Diagnosis: Diagnosed through clinical interviews, DSM-5 criteria, and tools like the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Symptoms include repetitive cleaning, counting, or checking behaviors.