This randomized controlled trial aims to evaluate the effects of digital mindfulness-based therapy in people with obsessive-compulsive disorder and to explore its possible psychological and neurophysiological mechanisms.

A total of 150 participants with a primary diagnosis of obsessive-compulsive disorder will be randomly assigned in a 1:1:1 ratio to one of three groups: digital mindfulness-based therapy, routine pharmacological treatment, or digital mindfulness-based therapy combined with routine pharmacological treatment.

The digital mindfulness-based therapy program will last for 6 weeks and will be delivered through a mobile mini-program using structured video and audio lessons, guided mindfulness practices, supervised weekly learning, and home practice. Participants in the pharmacological treatment group will receive routine pharmacological treatment for obsessive-compulsive disorder, and participants in the combined group will receive both interventions.

Changes in obsessive-compulsive symptoms, mindfulness, emotional symptoms, and other psychological outcomes will be assessed during treatment and follow-up. Heart rate variability will be assessed at baseline and weekly during the 6-week intervention. Electroencephalography will be assessed at baseline, at the end of the 6-week intervention, and at the 3-month and 6-month follow-up assessments to explore neurophysiological changes associated with treatment.

Obsessive-compulsive disorder is a disabling psychiatric condition characterized by persistent obsessions, compulsions, or both. Although pharmacological treatment and cognitive behavioral interventions are effective for many patients, some individuals continue to experience residual symptoms, poor treatment adherence, limited access to psychotherapy, or difficulty tolerating intensive symptom-focused interventions.

Digital mindfulness-based therapy may provide a more accessible and standardized psychological intervention. The intervention used in this study is a 6-week structured program delivered through a mobile mini-program. It includes psychoeducation, guided video and audio lessons, mindfulness meditation practices, supervised weekly learning, and home practice. The course covers mindful breathing, body scan, mindful movement, awareness of thoughts and emotions, acceptance-based practices, and compassion-related exercises.

Eligible participants will be randomly assigned in a 1:1:1 ratio to digital mindfulness-based therapy, routine pharmacological treatment, or digital mindfulness-based therapy combined with routine pharmacological treatment. Clinical and psychological assessments will be conducted at baseline, weekly during the 6-week intervention, and at 1, 3, 6, and 12 months after the intervention.

The primary clinical outcome will be the change in obsessive-compulsive symptom severity measured using the Yale-Brown Obsessive Compulsive Scale from baseline to the end of the 6-week intervention. Repeated assessments during treatment and follow-up will be used to examine symptom trajectories and the maintenance of treatment effects. Secondary psychological outcomes will include changes in mindfulness, thought-action fusion, self-compassion, depression, anxiety, and other related psychological characteristics.

Heart rate variability will be assessed at baseline and weekly during the 6-week intervention using time-domain, frequency-domain, and nonlinear measures to examine changes in autonomic nervous system regulation. Electroencephalography will be collected at baseline, at the end of the 6-week intervention, and at the 3-month and 6-month follow-up assessments. Electroencephalographic measures will include the mean amplitude and latency of the N200 and P300 event-related potential components. These measures will be used to explore psychological and neurophysiological mechanisms associated with improvement in obsessive-compulsive symptoms.

Inclusion Criteria:

1. A primary diagnosis of obsessive-compulsive disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5).
2. Aged 12 to 65 years.
3. Primary school education or above and able to understand the study procedures and complete the required assessments.
4. Willing and able to provide written informed consent. For participants under 18 years of age, written informed consent will also be obtained from a parent or legal guardian.
5. Participants who are already receiving psychotropic medication must have maintained a stable medication regimen for at least 4 weeks before enrollment. Any clinically necessary medication changes during the study will be documented.

Exclusion Criteria:

1. Current or lifetime diagnosis of schizophrenia spectrum disorder, bipolar disorder, substance use disorder, or personality disorder.
2. Severe physical illness or central nervous system disease that may interfere with participation in the study.
3. Severe suicidal ideation or suicidal behavior within the past month.
4. Pregnancy, planned pregnancy, or breastfeeding.
5. Concurrent participation in another psychotherapy program or clinical trial.
6. Mindfulness practice within the past month.
7. Inability to understand or comply with the study procedures.

Individual participant data will not be made publicly available because the dataset contains sensitive clinical, psychological, and neurophysiological information, and the informed consent and ethics approval do not currently include provisions for public sharing of participant-level data. Deidentified aggregate data may be made available from the principal investigator upon reasonable request, subject to ethical approval and institutional data protection requirements.

Due to the nature of the psychological and behavioral intervention, participants and intervention providers cannot be blinded to treatment allocation. Clinical outcome assessments will be conducted by trained assessors who are independent of intervention delivery and blinded to group assignment. Participants will be instructed not to disclose their treatment allocation to the outcome assessors.