Circulating Oxytocin Changes in Response to MDMA vs. Placebo in Adult Patients With Autism Spectrum Disorder and Matched Healthy Controls

Inclusion Criteria for patients:

* Adult patients with a confirmed diagnosis of autism spectrum disorder level 1 according to Diagnostic and Statistical Manual (DSM) V

Inclusion criteria for healthy controls:

* Adult healthy controls
* Matched for age, sex, BMI, and oestrogen replacement/menopause/hormonal contraceptives to patients
* No medication, except hormonal contraception
* A score of \<32 in the Autism Spectrum Quotient

Exclusion Criteria:

* Participation in a trial with investigational drugs within 30 days
* Illicit substance use (except for cannabis) more than 10 times in lifetime or any time within the previous two months
* Consumption of alcoholic beverages \>15 drinks/week
* Tobacco smoking \>10 cigarettes/day
* Cardiovascular disease (coronary artery disease, heart failure, left ventricular ejection fraction (LVEF) \<40%, stroke in the last 3 months, atrial fibrillation/flutter, Wolff-Parkinson-White (WPW)-Syndrome)
* Uncontrolled arterial hypertension (\>140/90 mmHg) or hypotension (\<85mmHg)
* Current or previous major psychiatric disorder (e.g., major depression, schizophrenia spectrum disorder)
* Psychotic disorder in first-degree relatives
* Pregnancy and breastfeeding
* Diagnosed CKD \> grade III (GFR \< 30ml/min)
* Diagnosed liver cirrhosis or alanine aminotransferase (ALAT) or aspartate aminotransferase (ASAT) levels 2.5 times above the normal range
* Confirmed epilepsy diagnosis
* Diagnosed autism spectrum disorder level 2 or 3 (according to DSM V criteria)