Research indicates that a single dose of LSD may alleviate anxiety without causing lasting side effects.

“We are conducting the first modern examination of LSD and its effects on common anxiety disorders,” says Dan Carlin from Mindmed in New York.

This disorder is marked by persistent worry about various issues, including work and relationships. Standard treatments often involve mood-enhancing medications and therapies, like selective serotonin reuptake inhibitors (SSRIs) and other antidepressants.

However, approximately half of patients do not respond to these treatments. “SSRIs are ineffective for many; they can produce side effects, such as emotional numbness, and must be taken daily to have any effect,” Carlin explains.

Previous studies propose that LSD might serve as an alternative treatment. Psychedelics are frequently used for their mind-altering hallucinations in recreational contexts. Carlin believes they may operate by enhancing serotonin levels in the brain, which improve mood, and may also encourage the brain’s capacity for rewiring and developing new thought patterns.

Nonetheless, so far, trials directly comparing LSD with a placebo have not specifically evaluated its effects on generalized anxiety disorder.

To address this issue, Carlin and his team recruited 198 adults with this condition. Participants gradually reduced their current anxiety medications, while those receiving psychotherapy continued their sessions.

In a standard clinical assessment, participants rated the intensity of 14 symptoms, including worry, tension, and difficulty focusing, on a scale from 0-4.

The team then randomly assigned participants into five groups—those receiving LSD (in doses of 25, 50, 100, or 200 micrograms) or placebo tablets. The following day, those who received doses of 100 and 200 micrograms reported greater symptom relief compared to other groups, according to Karlin.

One month later, participants who took the 100 and 200 microgram doses noted an average anxiety reduction of 21 and 19 points, respectively, with improvements sustained until the study’s conclusion three months later. Approximately 46% of these individuals were in remission.

In contrast, those receiving placebo and the lower doses experienced a 14-17 point reduction in anxiety over the same period, with about 20% achieving remission. This indicates that the lower doses did not yield significant benefits beyond the placebo effect.

The enhancements seen with the higher doses are significantly greater than those produced by the placebo, states Sunjeev Kamboj from University College London. “This marks a clinically meaningful improvement in terms of distress and disability,” he notes.

The progress observed in the placebo group is a common occurrence in anxiety studies, likely influenced by factors such as participants’ enthusiasm and attention during the trial, Kamboj adds.

The team noted that they could accurately ascertain whether most participants received LSD or placebo. Psychedelics typically produce hallucinations, which can affect many individuals. Across all groups, participants experienced nausea and headaches about 12 hours post-treatment.

At lower LSD doses, those on placebo reported hallucinations significantly less frequently than at higher psychedelics doses. This complicates the assessment of whether the benefits observed are due to individual expectations based on perceived effects or the direct influence of the drug on the brain, Kamboj explains.

Despite these caveats, the study offers compelling evidence that LSD could be a viable anxiety treatment, he states. “It’s a promising finding, indicating it can quickly alleviate symptoms. This is highly relevant for patients.”

The results have led the US Food and Drug Administration to classify MindMed’s LSD formulations as a breakthrough therapy, expediting the drug development process. Karlin mentions that the team has conducted thorough follow-up trials for over three months, with anticipated results forthcoming in the next few years.