A meta-analytic study looking into the safety and efficacy of LSD for treating mental health disorders found that its effectiveness largely depends on the type of disorder. While the analysis found no conclusive evidence for treating anxiety or depression, the analyzed studies indicated that LSD has a small but statistically significant positive effect when used to treat substance use disorders. The paper was published in Psychiatry Research.

LSD, or lysergic acid diethylamide, is a powerful hallucinogenic drug first synthesized in 1938 by Swiss chemist Albert Hofmann. It is derived from lysergic acid, a substance found in the ergot fungus that grows on rye and other grains.

LSD is known for its profound psychological effects, called a “trip,” which can include visual and auditory hallucinations, an altered sense of time, and intense emotional experiences. It is usually taken orally, on small pieces of paper called “blotters” that are soaked in the drug. The effects typically begin within 30 to 90 minutes after ingestion and can last up to 12 hours. The experience can be pleasant or frightening depending on the user’s mood, environment, and dose. LSD does not cause physical addiction, but it can lead to psychological dependence and tolerance. Some users report lasting changes in perception, such as visual distortions or flashbacks, long after use.

In most countries, LSD is classified as an illegal substance due to its potent effects and potential risks. Despite this, it is being studied for potential therapeutic uses in treating anxiety, depression, and addiction under controlled medical conditions.

Study authors Maria Helha Fernandes-Nascimento and her colleagues wanted to evaluate the efficacy and safety of LSD in the treatment of various mental disorders, including depression, anxiety, and substance use disorders in patients over 18 years of age. They conducted a systematic review and a meta-analysis, a method that involves statistically integrating the findings of multiple previous studies.

These authors searched nine databases of scientific publications, including Embase, PubMed, and Scopus, to find studies conducted on adults that investigated the efficacy and safety of LSD. They focused on randomized controlled trials (RCTs)—studies where researchers actively assign participants to receive either LSD or a control treatment. They excluded observational studies where researchers only recorded participants’ pre-existing use of LSD.

Their initial search identified 3,133 records. However, after removing duplicates and publications that did not meet their strict criteria, they ended up with a set of 11 studies to be included in the analysis. All of these 11 studies were double-blind, meaning that neither the participants nor the researchers administering the treatment knew who was receiving LSD versus a control substance (like a placebo or a different active drug).

Results showed that LSD administration was associated with a small, statistically significant beneficial effect on substance use disorders. Notably, the effects on substance use disorders reported by different studies were very consistent with one another, which increases confidence in this particular finding.

Regarding safety, the authors noted that the evidence was difficult to interpret. While five of the 11 studies (45%) did not report any adverse events, the paper suggests this may reflect poor reporting standards in the older trials rather than an actual absence of side effects. Other studies in the analysis did report adverse events, including serious ones such as acute anxiety and delusions during an LSD session, seizures, and cases requiring extended hospitalization.

“The effectiveness of LSD appears to vary significantly depending on the type of mental disorder treated. Results suggest a positive effect on substance use disorders. High heterogeneity requires caution and highlights the need for more double-blind RCTs [randomized controlled trials],” the study authors concluded.

The study contributes to the exploration of the potential use of LSD in treating mental health disorders. However, the authors note that most of the studies included in their analysis were conducted in the 1960s and 1970s, with only three studies conducted in more recent years, underscoring a need for modern research.

The paper, “Efficacy and Safety of LSD in the treatment of mental and substance use disorders: A systematic review of randomized controlled trials,” was authored by Maria Helha Fernandes-Nascimento, Priscila Weber, and Andre Brooking Negrao.