Study finds microdosing LSD is not effective in reducing ADHD symptoms

A new clinical trial has found that taking low doses of LSD twice a week does not reduce symptoms of attention-deficit/hyperactivity disorder in adults more than a placebo. While both the LSD and placebo groups showed improvements over six weeks, there was no meaningful difference between the two. These results challenge popular claims about the benefits of microdosing psychedelics and emphasize the importance of placebo-controlled studies when evaluating treatments that are often promoted through anecdotal evidence. The research was published in JAMA Psychiatry.

Attention-deficit/hyperactivity disorder, more commonly known as ADHD, affects nearly three percent of adults worldwide. The condition involves persistent difficulties with attention, impulsivity, and hyperactivity, often leading to significant struggles in work, relationships, and daily functioning. Standard treatments typically include stimulant medications like amphetamines or methylphenidate, which can be effective but don’t work for everyone. About one in three patients don’t get enough relief, and many stop taking the medications due to side effects or concerns about long-term use.

In recent years, the idea of microdosing psychedelics—taking very small amounts of substances like LSD or psilocybin—has gained popularity. Some users claim that microdosing improves focus, emotional balance, and creativity, and many report using it to self-treat conditions such as depression, anxiety, and ADHD. Microdoses are usually about one-tenth of a recreational dose, small enough that they don’t cause noticeable changes in perception. But despite the enthusiasm online and in the media, there has been little clinical research testing whether microdosing actually works as a treatment.

To test these claims, researchers from University Hospital Basel in Switzerland and Maastricht University in the Netherlands conducted a six-week, placebo-controlled trial. They recruited 53 adults diagnosed with moderate to severe ADHD and randomly assigned them to receive either a low dose of LSD or a placebo. The study was double-blind, meaning neither the participants nor the researchers knew who was receiving which treatment.

“We were contracted by the company Mindmed to perform this work which was within our line of work on psychedelics,” explained study author Matthias Liechti, the head of the Clinical Pharmacology Division of the University Hospital Basel.

Participants were given their assigned substance twice a week under supervision. The dose of LSD—20 micrograms—is considered to be at the higher end of the microdosing range and was chosen to increase the chance of detecting any therapeutic benefit. Throughout the study, participants completed various assessments measuring ADHD symptoms, including both self-reported and observer-rated scales. Researchers also collected information about side effects, vital signs, and subjective drug experiences.

By the end of the six weeks, both the LSD and placebo groups had shown significant reductions in ADHD symptoms. On the primary measure, symptoms improved by an average of 7.1 points in the LSD group and 8.9 points in the placebo group. This difference was not statistically meaningful. Across all other symptom ratings and time points, the two groups continued to show nearly identical improvements.

Participants in both groups also experienced similar benefits when they believed they were receiving the active drug. Interestingly, after the final dose, 80% of participants—whether they had taken LSD or placebo—guessed they had received LSD. Those who believed they had taken LSD tended to report greater symptom improvement, regardless of what they had actually received. This suggests that expectations may have played a large role in how participants experienced the treatment.

“In a well-designed study, low dose LSD (microdosing) is not more effective than placebo in patients with ADHD,” Liechti told PsyPost. “We observed marked therapeutic improvements in many patients and were surprised to see at the end of the study that they were equally frequent in the placebo group. Both LSD and placebo are effective over time but placebo and expectancy effects are the reason for this, not the LSD effect. This highlights the need for a well-blinded placebo control group.”

As expected, participants who took LSD did experience more noticeable short-term drug effects, such as changes in perception and feelings of altered consciousness. These effects were mild but significantly stronger than those reported by the placebo group. Still, the LSD dose used in the study was well tolerated overall. The most common side effects were headache, nausea, fatigue, insomnia, and mild visual changes. Two participants dropped out of the LSD group due to uncomfortable effects. There were no serious medical events or psychiatric complications.

Although the study did not find LSD to be effective for treating ADHD, it does offer some important insights. First, it shows that low doses of LSD can produce measurable but tolerable psychological effects in a clinical setting. It also demonstrates that strong placebo responses are possible in psychedelic studies, even when the dose is too low to cause intense hallucinations. This supports concerns that anecdotal reports of success with microdosing may be driven more by belief than biology.

The researchers also noted that the study was one of the few in psychedelic research to achieve successful blinding. In most psychedelic trials, the noticeable effects of high doses make it easy for participants to guess whether they’re receiving the active substance. In this case, the use of a low dose meant that even placebo recipients often believed they had received LSD, reducing the influence of expectation bias to some extent.

Although some past studies have suggested that higher doses of LSD may help with anxiety or depression, this trial does not provide evidence that low doses help with ADHD. Further research is needed to explore other psychedelics and different dosing schedules.

“The study used a relatively high dose of 20 micrograms, but a lower dose of 10 micrograms—or a dosing schedule of every day or every other day—might produce different results,” Liechti said. “It is not likely though. High-doses of LSD have consistently been shown to be effective in anxiety and depressive disorders. Thus, such high doses may also be effective in the treatment of mood in ADHD patients.”

The study, “Safety and Efficacy of Repeated Low-Dose LSD for ADHD Treatment in Adults: A Randomized Clinical Trial,” was authored by Lorenz Mueller, Joyce Santos de Jesus, Yasmin Schmid, Felix Müller, Anna Becker, Aaron Klaiber, Isabelle Straumann, Dino Luethi, Eline C. H. M. Haijen, Petra P. M. Hurks, Kim P. C. Kuypers, and Matthias E. Liechti.