LSD Treatment for Persons With Alcohol Use Disorder

Alcohol use causes more overall harm than any other drug and is the seventh leading risk factor for both deaths and disability-adjusted life years. Alcohol use disorders (AUD) are among the most common and undertreated mental disorders in developed countries. Pharmacological and psychotherapeutic treatments only show limited efficacy, and around 60% of the patients relapse in the short term after withdrawal.

Lysergic acid diethylamide (LSD) was investigated in numerous clinical trials during the 1950s and 1960s. Specifically, the use of LSD in the treatment of AUD was investigated extensively. A pooled analysis of six historical clinical trials demonstrated that a single dose of LSD significantly reduced alcohol use at three and six months after LSD administration. However, these trials are limited by several factors, including the use of diagnostic standards that are no longer up to date, single, high-dose treatment regimes, missing biological assessment for alcohol use, and no consequent assessment of blinding.

This trial will assess the efficacy and safety of two moderate to high doses of LSD to decrease alcohol consumption in patients with AUD. The trial has a double-blind, active placebo-controlled, randomized, parallel design and will be conducted in specialized treatment centers for addictive disorders in Switzerland. The study will include 128 patients who have undergone detoxification. Participants will be allocated to one of the two intervention arms (1:1 allocation). Each arm comprises nine study visits (no drug administration) and two study days (involving LSD administration) within 30 weeks. Patients allocated to the control intervention (active placebo group) will receive 10 µg LSD on the first study day and either 10 or 20 µg LSD on the second study day. Patients allocated to the treatment intervention will receive 150 µg LSD on the first study day and either 150 µg or 250 µg LSD on the second study day. The dose will be retained or increased depending on the patient's individual response on the first study day. Participants in the control intervention will be offered to attend an open-label LSD session (150 µg) at week 31. The open-label phase will comprise three additional visits. This trial will further compare the effectiveness of LSD-assisted therapy in both group and individual therapeutic settings. To this end, participants in both drug conditions will be randomly assigned to group or individual settings.

The primary outcome is the mean of percent heavy drinking days after administration of two doses of LSD during the 12 weeks following the second administration. Secondary objectives: The second aim of this study is to explore long-term changes in the cortical thickness, white matter microstructure, resting state functional connectivity (rs-FC) and cerebral blood flow (CBF) of regions associated with addiction pathophysiology. Furthermore, we will assess alterations in depressive symptoms, anxiety, and persisting effects of LSD. We will also assess biological markers of alcohol use and several predictors for treatment-response (genetics, personality traits, blinding, expectancy, and quality of acute drug effects). Lastly, we will compare LSD treatment within a group setting with treatment within an individual setting.