ICBT for OCD in Children With Autism

Inclusion Criteria: 1. A diagnosis of autism, based on the diagnostic criteria of the 4th or 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM) or the 10th edition of the International Classification of Diseases (ICD-10). Informed by the parent/caregiver and subsequently confirmed by review of the medical record or the neurodevelopmental assessment report. A diagnosis of autism will be considered present if it was established with validated instruments, such as the Autism Diagnostic Interview-Revised (ADI-R), the Autism Diagnostic Observation Schedule (ADOS) edition 1 or 2 or the Diagnostic Interview for Social and Communication Disorders (DISCO; autism or ASD cut-offs). 2. A DSM-5 or ICD-10 diagnosis of OCD. Confirmed by the assessor at the inclusion assessment, based on a structured diagnostic interview. 3. A total score of ≥16 on the CY-BOCS. Confirmed by the assessor at the inclusion assessment. 4. Age between 7 and 17 years. Confirmed by the caregiver and subsequently by the medical record system. 5. Ability to read and write Swedish. Confirmed by the caregiver at the telephone screening or/and the inclusion assessment. 6. Regular access to a computer or a smartphone/tablet connected to the internet, and a mobile phone to receive text messages. Confirmed by the caregiver at the telephone screening or/and inclusion assessment. 7. A parent/caregiver able to participate in the treatment alongside their child. Confirmed by the caregiver at the telephone screening or/and the inclusion assessment. Exclusion Criteria: 1. Global intellectual disability. Informed by the parent/caregiver and subsequently confirmed by review of the medical record or the neurodevelopmental assessment report, and additionally estimated with the two subtests matrix reasoning and similarities from the Wechsler Intelligence Scale for Children - fifth edition (WISC-V) or Wechsler Adult Intelligence Scale - fourth edition (WAIS-IV). 2. Comorbid psychotic disorder, bipolar disorder, severe eating disorder, severe depression, alcohol/substance dependence or hoarding disorder. Confirmed by the caregiver at the telephone screening and subsequently by the assessor at the inclusion assessment based on the structured diagnostic interview and, if required, the medical record. 3. Current suicidal intent or a previous suicide attempt within the last 12 months. Confirmed by the assessor at the inclusion assessment and, if required, the medical record. 4. Main symptom presentation consists of hoarding symptoms. Confirmed by the assessor at the inclusion assessment. 5. Completed CBT for OCD within the last 12 months prior to the inclusion assessment (defined as at least 5 sessions of CBT including ERP). Confirmed by the caregiver at the telephone screening or/and inclusion assessment and, if required, the medical record. 6. Simultaneous psychological treatment for OCD or anxiety. Confirmed by the caregiver at the telephone screening and/or inclusion assessment. 7. Initiation, dosage change or cessation of medication for OCD (primarily selective serotonin reuptake inhibitors, SSRIs) or behavioural symptoms of ASD (atypical antipsychotics) within the 6 weeks prior to the baseline assessment. Confirmed by the caregiver at the telephone screening and the inclusion assessment and, if required, the medical record. 8. Having a close relationship to an already included participant (e.g., sibling, cousin), to avoid being randomised into two different arms, with the risk of information "leaking" between the groups. Confirmed by the caregiver or assessor at the telephone screening and/or at the inclusion assessment.