LSD for anxiety: a single dose with effects lasting up to 12 weeks

Until now, pharmacological treatments for generalized anxiety disorder have generally been approached as therapies that require continuity over time. A phase 3 trial has now evaluated a very different possibility: administering a single dose of lysergide (in other words, LSD in its pharmaceutical form, studied as DT120) and monitoring how symptoms evolve over the following three months.

The first results from the Panorama study, announced on September 14 by Definium Therapeutics, show a greater reduction in anxiety than that observed with placebo, and that difference was still present 12 weeks after administration. It is an important result, although it should be interpreted with caution since, for now, only the preliminary data reported by the company are available, rather than a complete scientific publication.

One dose and 12 weeks of follow-up

Panorama included 245 adults aged between 18 and 74 diagnosed with generalized anxiety disorder and symptoms of at least moderate severity. Participants were randomly assigned to receive 100 micrograms of DT120, a 50-microgram dose, or placebo.

The main comparison was between the 100-microgram and placebo groups. Progress was measured using the Hamilton Anxiety Rating Scale (HAM-A), a clinical tool used to assess the severity of psychological and physical symptoms associated with the disorder.

At the start of the study, both groups had almost identical scores, at around 28 points. After 12 weeks, the adjusted mean reduction was 9.8 points with DT120 and 4.7 with placebo, a difference of 5.1 points between the two groups.

Researchers also looked at how many participants reduced their initial score by at least half. This was achieved by 32% of those who received 100 micrograms, compared with 14% in the placebo group. In addition, 15% met the criteria for remission, compared with 4%.

The differences began to appear very early. Some secondary assessments detected changes from the day after treatment and during the first week, with those differences continuing to appear in later measurements. At the end of the 12 weeks, the treated group was still showing a better overall outcome than the placebo group, although the response was not the same for every participant.

A result that had already been seen before

Panorama is not the first advanced trial to report this effect. In August, another phase 3 study called Voyage evaluated 214 adults with generalized anxiety disorder and found a 5.4-point difference on the HAM-A scale compared with placebo after 12 weeks, very close to the result now reported.

These findings also build on a phase 2b trial involving 198 people, published in JAMA in 2025. That study compared different doses of lysergide and helped select the 100-microgram dose for the next stages of development. The 200-microgram dose, however, caused more adverse effects without showing a clear additional improvement in efficacy.

The fact that two independent phase 3 trials have produced results in the same direction strengthens the clinical signal. Full publication of these studies will make it possible to assess aspects that preliminary data cannot yet show in the same level of detail, from a complete safety analysis to the characteristics of participants who responded better or worse.

How can an effect lasting hours be associated with changes lasting weeks?

LSD interacts with several receptors in the brain, although many of its psychedelic effects are linked to the 5-HT2A serotonin receptor. For several hours, it can alter perception, cognition, and the way different regions of the brain process information.

What is still not fully understood is why this relatively short-lived action could be associated with much longer-lasting clinical changes.

One of the hypotheses being studied involves neuroplasticity, the brain’s ability to modify connections and reorganize certain neural circuits. Research into serotonergic psychedelics is also examining whether the psychological experience that occurs during the hours of acute effects may later contribute to changes in patterns associated with anxiety.

At present, none of these explanations is enough to establish the exact mechanism responsible. This is precisely why the phase 2b trial published in JAMA is relevant: the protocol prevented the professionals accompanying participants from providing psychotherapy during the session, allowing researchers to better isolate the effect of the drug itself without adding another therapy at the same time.

Not a treatment to take at home

The context in which DT120 is administered is essential to understanding these results. Participants were not given the medication to use on their own, but received it during supervised sessions lasting several hours.

In Panorama, they remained under clinical observation for at least eight hours. With the 100-microgram dose, the average time needed to meet the criteria for ending the session was 6.2 hours, and 94% of participants had met those criteria before the eighth hour.

Adverse effects were common, although most were described as mild or moderate and were concentrated on the same day. A total of 94.8% of the group receiving 100 micrograms experienced at least one, compared with 62.9% in the placebo group. The most common were illusions or perceptual disturbances, reported in 68%; nausea, in 37%; and headache, in 24%. The company reported no serious adverse events related to the drug during this phase.

These conditions are important when distinguishing this research from recreational LSD use. The potential treatment is being studied using defined doses, prior patient selection, and professional supervision during the period of acute effects.

What still remains to be understood

The 12 weeks do not mark the end of the Panorama study. After the placebo-controlled phase, the trial continues with an additional 40 weeks of open-label follow-up, during which some participants may receive further doses if their symptoms return to certain predefined levels. This phase will help researchers study how long the improvement may last and how often treatment might need to be repeated.

There is also a particularly important challenge in psychedelic trials: preventing participants from knowing whether they received the active drug or placebo. Perceptual changes can make someone suspect which treatment they received, potentially influencing their expectations and, in turn, the assessment of the results. Panorama included a 50-microgram group, among other reasons, to help reduce this problem, although it will remain an important factor when interpreting the full data.

DT120 remains an experimental treatment and is not currently approved for generalized anxiety disorder. Definium Therapeutics plans to meet with the US Food and Drug Administration before submitting an application for approval, currently expected in the first half of 2027.

What these trials are beginning to explore is an unusual approach in psychiatry: whether an administration lasting only a few hours can be associated with an improvement that remains measurable several weeks later. Determining how long that effect really lasts, which patients are most likely to benefit, and how it can be used safely will ultimately determine whether this possibility makes its way into clinical practice.