The goal of this multiple baseline case series study is to test the effect of imagery rescripting (ImRs) in Obsessive Compulsive Disorder (OCD) and Body Dysmorphic Disorder (BDD).

Primary objective :The course of schema or core beliefs and change in OCD and BDD. To investigate the effectiveness of imagery rescripting on factors presumed to underlie the disorder, according to schema theory, and on OCD and BDD symptoms.

Secondary objective: The change in OCD and BDD symptoms (full questionnaire), schemata and modes, core emotions, mood, affect and obtrusiveness of intrusion.

Other objectives are research into the working mechanisms of imagery rescripting by collecting qualitative data from patients and their practitioner in a qualitative interview.

For this study, a multiple-baseline single-case experimental design (SCED) is used testing different outcome variables in 18 OCD patients and 18 BDD patients. After a variable baseline period of 3-8 weeks participants will start twice weekly with imagery rescripting for 12 sessions, followed by a 6 week follow up.

Participants will rate schema- or core beliefs and OCD or BDD severity on a visual analogue scale. In addition participants will rate core emotions, affect and obtrusiveness of the intrusion. Secondary we will asses four times questionnaires about OCD of BDD symptoms, depression and schemas en modes. After treatment participants will be interviewed about their experiences.

In a multiple baseline case series study the effectiveness of Imagery Rescripting (ImRs) as a treatment for Body Dysmorphic Disorder (BDD) and Obsessive Compulsive Disorder (OCD) will be researched. 18 participants with OCD and 18 participants with BDD will be randomized to a waiting list with variable length between 3-8 weeks. After this participants will enter a 1-3 session for preparation followed by 12 sessions with ImRs, given twice-weekly. Follow up assessment will take place 6 weeks after ending treatment. Primary outcome is schema of core beliefs and OCD or BDD symptoms, operationalized by daily measures with visual analogue scales. Also 4 times the investigator measures the OCD or BDD symptoms with the Yale Brown Obsessive Compulsive Scale (Y-BOCS), depression with the Hamilton Depression Rating Scale (HDRS) and 3 times the schema and mode questionnaires with the Young Schema Questionnaire (YSQ) and de Schema Mode Inventory (SMI). The hypothesis is that the primary outcomes will reduce more during the intervention phase compared to the baseline phase and remain stable or even further improve in the follow-up phase. For the secondary outcomes the investigator hypothesized a decrease in depressive symptoms, a decrease in the emotions guilt or shame and first an increase in sadness, fear and angriness followed by an decrease. The largest effect is expected from pre- to post treatment, with a relative stable little change during baseline and follow-up.

Results will be analyzed using visual inspection, repeated measures ANOVA and multilevel analysis, pooling the effects of the individual cases. Finally, participants will be interviewed post treatment about their experiences during treatment.

Inclusion Criteria:

• Meet the criteria for OCD or BDD, a primary diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5)
• Are aged 18 and beyond
• Dutch literacy
• Cut-off Y-BOCS of 20
• No change in medication. Stable dose at least 6 weeks prior to study.

Exclusion Criteria:

• Current (hypo)mania
• Active suicidal plans
• Current psychosis (excluding delusional symptoms related to disorder)
• Alcohol or drugs abuse as diagnosed by Diagnostic and Statistical Manual of Mental Disorders (DSM-5)
• Electroconvulsive therapy in last 6 months
• Neurological disorder or Intelligence Quotient < 80

Due to privacy regulations patient data will not be shared unless the European Union (EU) regulations on data protection are guaranteed.