The Role of Serotonin in Compulsive Behavior in Humans: Underlying Brain Mechanisms

Who can take part

• Individuals with high scores on obsessive-compulsive traits (with or without a diagnosis of OCD established by a psychiatrist) and healthy volunteers (male or female) between 18 and 70 years. Compulsive individuals without an OCD diagnosis are individuals without a history of psychiatric or other major medical conditions but scoring abnormally high on the Obsessive-Compulsive Inventory (OCI) questionnaire

Who cannot take part

• Current or previous neurological disease, severe somatic disease, or consumption of medical drugs likely to influence the test results
• Contraindications for MRI (pacemaker, metal implants, etc.)
• Alcohol or drug abuse
• Drug use other than tobacco and alcohol within the last 30 days
• Drugs > 10 x lifetime (for each substance)
• Current medication with serotonergic acting compounds. Use of other psychoactive substances must be stable at least one month prior to inclusion and maintained throughout the study
• Allergy to the ingredients in the administered drug
• Dizzy when changing from supine to upright position (e.g. postural orthostatic tachycardia syndrome)
• Mild hypotension (blood pressure below 100/70 mmHg) or hypertension (blood pressure above 140/90 mmHg)
• For the OCD group: other Axis I mental disorder as primary diagnosis according to ICD-10 criteria
• For healthy volunteers: any current or former primary psychiatric disorder (Axis I WHO ICD-10 diagnostic classification)
• Abnormal ECG (e.g. prolonged QT syndrome)
• Non- fluent in Danish or pronounced visual or auditory impairments
• Current or past learning disability
• Pregnancy
• Lactation
• Participation in experiments with radioactivity (> 10 mSv) within the last year or significant occupational exposure to radioactivity
• Head injury or concussion resulting in loss of consciousness for more than 2 min
• Hash > 50 x lifetime
• Severe physical impairments affecting eyesight or motor performance