LSD-Perceptual-Choice-Study

The study team will subject healthy participants to multiple perceptual decision-making tasks after the administration of low doses of LSD (d-lysergic acid diethylamide) as a pharmacological challenge. The investigators want to illuminate the behavioral and neural effects of psychedelics on prior beliefs and evidence processing. Each subject will participate in 3 x 5 h study sessions separated by at least 7 days. Subjects will be under continuous supervision until approximately 4.5h after substance administration. The participants are asked to perform the following cognitive tasks alongside EEG measurement after administration of either LSD or placebo: Changepoint task, history bias task, surround suppression task, auditory steady-state response paradigm, motor localizer task.

Inclusion criteria

• Willingness to adhere to the study protocol and sign the consent form
• ≥ 18 and ≤ 65 years of age at Screening
• Body mass index 18-29
• Fluent understanding of German
• Normal or corrected-to-normal vision
• Willingness to not operate a traffic vehicle or heavy machinery 24 hours after substance administration
• Willingness to refrain from taking illicit psychoactive substances, including cannabis, for the duration of the study
• Willingness to not consume more than one alcoholic standard drink the night before the study sessions and not consume alcohol for 24 h after each study session
• Willingness to abstain from xanthine-based liquids from the evenings prior to the study sessions and during the sessions
• Willingness to use effective birth-control throughout the study duration
• Adequate task performance in the decision-making tasks during a practice session in the screening visit

Exclusion criteria

• Recent (<30 days) or current participation in another clinical trial
• Women that are pregnant, nursing, or planning to become pregnant during the study period
• Current use of contraindicated/psychoactive medications or illicit drugs
• Lifetime use of classical psychedelics more than 20 times, or any time within the previous two months
• Consumption of >5 cigarettes per day or >20 alcoholic standard drinks per week
• Severe chronic or acute medical condition
• Hypertension (>140/90 mmHg) or hypotension (<85mmHg systolic)
• Current or lifetime major mental health disorder
• Personal or family (first-degree) history of a primary psychotic disorder