Precision Brain Mapping to Predict and Track Response to Exposure and Response Prevention Therapy in Youth With Obsessive-Compulsive Disorder

Inclusion Criteria: * Age 10 to 17 years at the time of initial consent. Participants who reach age 18 while enrolled may remain in the study after completing the adult re-consent process; no new participants age 18 years or older will be recruited. * DSM-5 diagnosis of obsessive-compulsive disorder, established through a clinical interview by a clinician. * Parent or guardian able to provide informed consent and participant able to provide assent. * Participant has sufficient English fluency to complete cognitive tasks and assessments. Parent or guardian English fluency is not required; interpreter support is available. Exclusion Criteria: * History or current evidence of a significant neurological disorder, including but not limited to seizure disorder, stroke, or traumatic brain injury with loss of consciousness. * Any standard MRI contraindication identified during initial screening or on the MRI safety checklist, including but not limited to ferromagnetic implants, certain medical devices or metal fragments, severe claustrophobia, or pregnancy. * Pregnancy at screening or pregnancy identified during study participation. * Active suicidal ideation. * Any psychiatric condition that, in the investigator's judgment, would interfere with study participation or data interpretation, including but not limited to psychotic disorders, bipolar disorders, severe neurodevelopmental disorders, intellectual disability, severe eating disorders, or recent significant substance use dis…