Study: NCT05528224

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: stepped-care Internet-based cognitive behavioral therapy(SC-ICBT)
Description: OCD patients will take part in four structured online lessons for 6 weeks. Lesson one: Psychological Health Education, including the knowledge about OCD, SUDs and other related information.~Lesson two: Exposure and Response Prevention (ERP), including the knowledge about ERP, exposure item list and other related information.~Lesson three: Practice of Exposure and Response Prevention. Patients are asked to perform ERP practice based on what they have learned previously: practice at least once a day, a day about one hour all together. On this basis, in the main study, patients with severe obsessive and compulsive symptoms(Y-BOCS≥24) will be provided with extra therapist-guided ICBT: twice a week, about an hour one time. While in the pilot study, non-responders at week 3(YBOCS score reduction rate\<25%) will be provided with extra therapist-guided ICBT.~Lesson four: Practice retrospection and relapse prevention.

Intervention type: OTHER
Group type: ACTIVE_COMPARATOR
Intervention: Cognitive Behavioral Group Therapy (CBGT)
Description: OCD patients will be asked to come to Shanghai Mental Health Center to take part in the offline CBT group. Each group will be treated for 6 weeks, twice a week for 2 hours each time. The treatment was supervised by an experienced CBGT therapist. The structure of the course basically corresponds with the SC-ICBT group.

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: conventional medical treatment (TAU)
Description: In this study, the investigators use selective serotonin reuptake inhibitors (SSRIs) approved by the State Food and Drug Administration (CFDA) for the treatment of OCD (i.e., fluoxetine, paroxetine, sertraline and fluvoxamine) as well as citalopram and escitalopram. The second-generation atypical antipsychotics may also be combined as a potentiator if the patient requires.~The maximum dosage shall not exceed the maximum dosage prescribed in the instruction manual.

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: conventional medical treatment (TAU)
Description: In this study, the investigators use selective serotonin reuptake inhibitors (SSRIs) approved by the State Food and Drug Administration (CFDA) for the treatment of OCD (i.e., fluoxetine, paroxetine, sertraline and fluvoxamine) as well as citalopram and escitalopram. The second-generation atypical antipsychotics may also be combined as a potentiator if the patient requires.~The maximum dosage shall not exceed the maximum dosage prescribed in the instruction manual.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: conventional medical treatment (TAU)
Description: In this study, the investigators use selective serotonin reuptake inhibitors (SSRIs) approved by the State Food and Drug Administration (CFDA) for the treatment of OCD (i.e., fluoxetine, paroxetine, sertraline and fluvoxamine) as well as citalopram and escitalopram. The second-generation atypical antipsychotics may also be combined as a potentiator if the patient requires.~The maximum dosage shall not exceed the maximum dosage prescribed in the instruction manual.