A randomized clinical trial published in JAMA on found that a single high microgram dose of LSD reduced symptoms of generalized anxiety disorder in many participants for at least 12 weeks. The U.S.-based study enrolled 194 adults with moderate to severe anxiety and reported the strongest clinical benefit at the 100-microgram dose.
Key takeaways
- The trial included 194 participants across the United States with moderate to severe generalized anxiety disorder.
- Only higher doses (100 or 200 micrograms) produced measurable benefit; 100 micrograms showed the best outcomes.
- At 12 weeks, about 47% of the 100‑microgram group met remission criteria; roughly 65% achieved a ≥50% symptom reduction.
- By comparison, about 20% of the placebo group were in remission at 12 weeks and ~30% had a ≥50% score drop.
- Baseline mean anxiety score was 30 on a 0–56 scale; remission was defined as ≤7. The 100‑microgram group averaged a 21‑point reduction.
- Common, expected acute effects included altered visual perception, nausea, headache and euphoric mood; hallucinations were reported by >90% of the 100‑microgram group and 100% of the 200‑microgram group.
- Follow-up was limited to three months, and 18% of participants were receiving external psychotherapy during the trial.
Verified facts
The multicenter, randomized trial compared placebo with four LSD dose levels (25, 50, 100 and 200 micrograms) in adults diagnosed with generalized anxiety disorder. Investigators measured symptoms using a standardized anxiety rating scale (0–56); an average baseline score was approximately 30, above the severe threshold of 24. The primary clinical signal appeared only at the two highest doses, with 100 micrograms producing the clearest benefit.
| Dose | Remission at 12 weeks | ≥50% symptom reduction |
|---|---|---|
| Placebo | ~20% | ~30% |
| 100 µg | ~47% | ~65% |
| 200 µg | Noted improvement (higher adverse effects) | Improvement observed |
The study recorded acute, expected psychedelic effects during the dosing sessions. Side effects were mostly transient and resolved after the session, but they were frequent enough that a minority of participants discontinued the trial. Two people reported feeling intoxicated during dosing (one in the 50‑µg group and one in the 100‑µg group) but were back to normal after the session.
Context & impact
Psychedelic compounds like LSD are proposed to transiently increase neural connectivity and plasticity, potentially disrupting entrenched anxiety-related thought patterns. Previous trials often combined psychedelics with psychotherapy, making it difficult to isolate the drug’s standalone effect. This trial deliberately enrolled many participants not undergoing formal psychotherapy to help clarify LSD’s independent contribution.
The results are notable because standard first-line anxiety treatments—SSRIs and benzodiazepines—leave an estimated half of patients without adequate relief. A single-dose intervention that yields durable improvement over months, if replicated, could change treatment options and regulatory considerations for psychedelic-assisted care.
Limitations
- Follow-up was limited to 12 weeks; durability beyond that is unknown.
- About 18% of participants continued external psychotherapy, complicating attribution of effects solely to the drug.
- High-dose groups reported frequent intense perceptual effects, which may limit tolerability for some patients.
“This study contributes valuable, controlled evidence to the emerging field of psychedelic therapeutics and suggests that LSD alone may have sustained anti-anxiety effects,”
Dr. Claudio Soares, Queen’s University School of Medicine (commentary)
Unconfirmed items
- Whether clinical benefits persist beyond 12 weeks after a single dose remains untested in this trial.
- The precise neurobiological mechanism linking LSD exposure to sustained anxiety relief is still hypothetical and under study.
- How outcomes compare across different patient subgroups or with adjunctive psychotherapy requires further trials.
Bottom line
This randomized study of 194 adults found that a single 100‑microgram dose of LSD produced clinically meaningful reductions in generalized anxiety symptoms that lasted at least three months for many participants. The result is promising but preliminary: larger, longer trials are needed to confirm durability, optimize dosing and assess long-term safety and tolerability.