Transcranial Direct Current Stimulation and Extinction in Obsessive Compulsive Disorder

Obsessive-compulsive disorder (OCD) is associated with substantial impairments in quality of life and is among the most disabling psychiatric disorders. Exposure therapy is among the first-line of treatments for obsessive-compulsive disorder (OCD) . Extinction learning is thought to be a core mechanism of therapeutic exposure. Fear and safety signal learning are traditionally associated with activity and connectivity within the canonical corticolimbic "fear circuit", which includes the amygdala, medial prefrontal cortex (mPFC), and hippocampus. Transcranial direct current stimulation (tDCS) is a neuromodulation technology that can augment brain plasticity, learning, and memory. The proposed study will test if obsessive-compulsive disorder (OCD) is associated with inhibitory safety learning deficits and if transcranial direct current stimulation (tDCS) normalizes functional connectivity and safety signal processing to recover extinction deficits in obsessive-compulsive disorder (OCD).

Inclusion Criteria: * All Participant Inclusion Criteria would include: 1. 18 years of age or older 2. speak English fluently, and 3. able to provide written and verbal informed consent. * Obsessive-compulsive disorder (OCD) Inclusion Criteria would include: 1. meet criteria for OCD as determined by structured clinical interview 2. exhibit significant current symptoms of OCD 3. report duration of OCD symptoms of at least 1-year 4. OCD symptoms are primary or co-primary relative to other psychiatric diagnoses 5. stable psychiatric treatment (≥8-weeks) or no active treatment. 6. exhibit significant current symptoms of OCD as determined by the Dimensional Obsessive-Compulsive Scale (DOCS) (≥18). Exclusion Criteria: * All Participant Exclusion Criteria would include: 1. active severe substance use disorder(s) 2. acute suicidality 3. history of bipolar or psychotic disorder(s) 4. significant developmental disabilities 5. loss of consciousness \> 10 minutes 6. history of traumatic brain injury 7. major neurological disease 8. a positive pregnancy test 9. other brain stimulation or magnetic resonance imaging contraindications 10. new psychological treatment within the past 8 weeks 11. daily anxiolytic medication use (e.g., benzodiazepine). * Non-Clinical Control Exclusion Criteria would include: 1. meet current criteria for a psychiatric disorder as determined by structured clinical interview 2. active-psychotropic medications.