This study aims to evaluate the efficacy of Temporal Interference (TI) stimulation in treating patients with obsessive-compulsive disorder (OCD) and to explore its potential neural mechanisms using magnetic resonance imaging (MRI) and electroencephalography (EEG).

This randomized, blind, multi-phase clinical trial aims to evaluate the efficacy of Temporal Interference (TI) stimulation in patients with treatment obsessive-compulsive disorder (OCD), and to compare the effects of stimulating different brain regions.

The study includes three phases:

• Phase 1: Patients are randomly assigned to receive either sham stimulation, bilateral nucleus accumbens (NAcc) stimulation, or bilateral bed nucleus of the stria terminalis (BNST) stimulation.
• Phase 2: Non-responders from Phase 1 enter a second phase, receiving stimulation to the opposite target region. Sham participants are re-randomized to NAcc or BNST.
• Phase 3 (Exploratory): Remaining non-responders may opt to receive stimulation targeting the caudate nucleus, the putamen, or the amygdala.

Stimulation is delivered twice daily for 7 days in each phase, followed by follow-up assessments for up to 4 weeks. Comprehensive clinical assessments, self-reported symptom scales, magnetic resonance imaging (MRI), electroencephalography (EEG), and cognitive function tests are conducted before and after each phase to ensure data consistency. Additionally, clinical assessments and self-reported scales are repeated 1 week after the end of each treatment phase.

Inclusion Criteria:

• 18-50 years old
• Diagnosis of OCD per DSM-5
• Y-BOCS score ≥20
• Have a documented history of at least two adequate trials of selective serotonin reuptake inhibitors (SSRIs). If currently receiving SSRI treatment, the dosage must be stable for at least 8 weeks prior to enrollment
• With at least 9 years of education

Exclusion Criteria:

• Any DSM-5 diagnosis other than OCD (except OCPD)
• OCD symptoms too severe to complete assessments
• Received electroconvulsive therapy (ECT) within the past 6 months
• Received other forms of neuromodulation within the past 2 months（see Item 3 for ECT）
• Severe medical illness or seizure risk (e.g., cardiovascular, respiratory conditions)
• Neurological disorders or history of brain injury/surgery
• MRI-incompatible implants (e.g., pacemaker, stents, cochlear implants).
• Current suicidal risk per investigator judgment
• Pregnant or planning pregnancy during the study
• Started structured OCD psychotherapy within 3 months, with expected change during treatment