Microdosing LSD Fails To Improve ADHD Symptoms

The perceived benefits of microdosing for attention-deficit/hyperactivity disorder (ADHD) may stem more from expectation than from actual pharmacological effects. That’s according to a new study from the University Hospital Basel in Switzerland and Maastricht University in the Netherlands, published in JAMA Psychiatry.

Understanding ADHD and challenges in treatment

ADHD is a common neurodevelopmental disorder affecting ~2.6% of adults worldwide. It is characterized by symptoms of inattention, hyperactivity and impulsivity, impairing daily functioning, occupational performance and overall quality of life. While pharmacological medications categorized as stimulants and nonstimulants are the standard of care, they are not universally effective. Studies indicate that up to 40% of patients do not achieve adequate symptom control, and many experience adverse effects that can lead to medication discontinuation.

Given these challenges, there is a growing interest in exploring alternative treatments for ADHD, including psychedelic microdosing.

Microdosing refers to the practice of taking small doses of psychedelics, such as lysergic acid diethylamide (LSD) or psilocybin, with the intention of enhancing cognitive function or alleviating psychiatric symptoms without inducing psychoactive effects. Typically, a microdose of LSD ranges from 5 to 20 µg, and users often follow a regimen of dosing every few days over several weeks. Anecdotal reports and naturalistic studies have suggested that microdosing LSD may alleviate symptoms of ADHD, including inattention and impulsivity, but controlled clinical evidence remains sparse.

Most evidence supporting microdosing for ADHD comes from self-reported improvements and observational data, lacking the rigorous controls necessary to establish causal relationships. A recent systematic review of microdosing studies emphasized the need for randomized controlled trials to validate claims of efficacy.

In an effort to explore whether microdosing LSD could improve symptoms of ADHD, researchers conducted a rigorous clinical trial to evaluate its safety and efficacy. The study aimed to determine whether the perceived benefits of microdosing hold up under scientific scrutiny or are merely driven by expectation.

Dr. Lorenz Müller, a lecturer in the Department of Pharmaceutical Sciences of the University of Basel, and colleagues conducted a double-blind and placebo-controlled phase 2A randomized clinical trial. The study took place over 6 weeks recruiting 53 adult participants, aged 18–65 years, diagnosed with moderate to severe ADHD.

Evaluating low-dose LSD for ADHD

The participants were randomly assigned in a 1:1 ratio to receive either 20 µg of LSD or a placebo, administered twice weekly under supervised conditions. They were then assessed using the Adult ADHD Investigator Symptom Rating Scale. Self-rated ADHD symptoms and observer-rated symptoms were also recorded using standardized rating scales. Safety outcomes were monitored, including adverse events and physical health parameters.

Both the LSD and placebo groups exhibited a significant reduction in ADHD symptoms over the six-week period. However, there was no statistically significant difference between the two groups.

“Although repeated low-dose LSD administration was safe in an outpatient setting, it failed to demonstrate efficacy compared with placebo in improving ADHD symptoms among adults,” said the authors.

The most common adverse effects reported were headache, nausea, fatigue, insomnia and visual alterations, however, there were no serious adverse events reported.

"A rather high microdose was selected to increase the likelihood of detecting a positive response and efficacy. Accordingly, we consider it unlikely that the dose was too low to be efficacious,” the authors added.

Many participants, even those in the placebo group, believed they had received LSD, which might have influenced their self-reported improvements. The authors noted that participants who believed they received LSD reported greater reductions in ADHD symptoms compared to those who correctly guessed their placebo allocation.

Implications of microdosing LSD for ADHD treatment

The findings of this study challenge the perception that microdosing LSD can effectively reduce ADHD symptoms.

"These results question the anecdotal practice and highlight the importance of placebo-controlled trials in low-dose psychedelic research,” said the authors.

The strong placebo response was likely influenced by high expectations and the extensive media coverage around the potential benefits of microdosing psychedelics, the authors said. The fact that many placebo group participants believed they had received LSD and subsequently reported symptom improvements underscores the impact of expectation bias.

"Observed benefits of psychedelic microdosing may be attributable more to expectancy than to pharmacological effects of the psychedelic itself,” they added.

Future research should aim to investigate alternative dosing regimens, such as lower doses or varied administration schedules and other psychedelic forms including psilocybin.

While microdosing remains a topic of public fascination, only controlled clinical studies can determine its true efficacy and safety.

Reference: Mueller L, Santos De Jesus J, Schmid Y, et al. Safety and efficacy of repeated low-dose LSD for ADHD treatment in adults: a randomized clinical trial. JAMA Psychiatry. 2025. doi: 10.1001/jamapsychiatry.2025.0044