A rigorous new study finds that a single dose of LSD can ease anxiety and depression for months.
The study involved 198 adults with generalized anxiety disorder, or GAD, a disabling form of anxiety that affects about one in 10 people over the course of a year.
Participants who got lower doses of LSD (25 or 50 micrograms) did no better than those who got a placebo. But people who received higher doses (100 or 200 micrograms) responded quickly, a team reports in the Journal of the American Medical Association.
"By the next day, they were showing strong improvements," says Dr. David Feifel of Kadima Neuropsyciatry Institute in San Diego, one of the 22 centers that participated in the study. "And those improvements held out all the way to the end of the study, which was 12 weeks."
But it's unclear whether some of the improvement was related to non-drug factors like the sensory environment in which people were treated, says Robin Carhart-Harris, a psychedelics researcher at the University of California, San Francisco who was not involved in the study.
"The safety looks good, the tolerability looks good," he says, "but where is the depth of information about the way you delivered this product?"
Carhart-Harris, like many scientists who study psychedelics, believes that successful treatment is more likely if a person has the right mindset when beginning a trip and if the trip occurs in a place with the right sensory environment.
Not your everyday anxiety
Generalized anxiety disorder involves extreme worry or dread that interferes with a person's ability to function.
"It's characterized by continuous worry, inability to relax, and all the physical manifestations, racing heart rates and sweatiness," Feifel says. It's also frequently accompanied by depression.
Current antidepressant and antianxiety drugs are inadequate for about half of people diagnosed with GAD.
So 22 outpatient psychiatric research sites agreed to test a proprietary form of LSD called MM120, which comes from the company MindMed.
The drug is not at all like Prozac or Zoloft, which are among the usual treatments for GAD.
"This is something that has a very, very distinct subjective experience," Feifel says, "what people might call a trip."
MM120, like other versions of LSD, can alter a person's perceptions and cause them to see, hear, or feel things that aren't there.
In the study, participants were far more likely to improve if they received a dose of MM120 high enough to induce a psychedelic experience. The higher doses also were more likely to lift a person's depression.
Non-drug factors
Psychedelic treatment often involves guides or therapists who help ensure that a patient's psychedelic experience is safe and effective. In addition, treatment centers often provide rooms with soft lighting, a naturalistic decor, and music or other sensory stimulation.
But in this study, it's unclear whether these environmental factors played an important role in the treatment.
The sessions were overseen by two "dosing session monitors," who also provided an education session about the treatment. The sessions were conducted in a "private aesthetically pleasant room," the researchers say, and participants were offered "standardized music and eyeshades."
All of these factors could have contributed to the outcome, Carhart-Harris says, but it's hard to tell because they weren't specified in the study protocol and could have varied greatly from one center to another.
"To not say anything about music listening, for example, when it's been present in virtually 100% of the trials that have been published to date on psychedelic therapy, is an obvious omission," Carhart-Harris says.
A psychedelic future
The new research represents an emerging trend in psychedelic research: bigger, more rigorous studies that are more likely to be supported by a pharmaceutical company.
Such studies are needed to get psychedelic drugs like LSD, MDMA and psilocybin approved by the Food and Drug Administration, Feifel says. And giving doctors access to approved psychedelics could "revolutionize treatment" of psychiatric conditions ranging from depression to PTSD and addiction.
"Give it a couple of years and we'll be seeing drugs like psilocybin [and] magic mushrooms as medicines," Carhart-Harris says. "A whole mindset shift is going to happen around that."
The FDA seems open to that possibility. It has already given MM120 "breakthrough therapy" status, which is meant to speed up the evaluation of promising new drugs.
MindMed, for its part, has already launched a pair of "phase 3" studies of MM120. The company expects to complete those trials in 2026.
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