Repeated LSD treatment for ADHD symptoms only as good as placebo

Repeated administration of low-dose lysergic acid diethylamide (LSD) in an outpatient setting is not necessarily better than placebo at reducing symptoms of attention-deficit/hyperactivity disorder (ADHD), according to the results of a phase IIA trial.

The 6-week trial included 53 adults (mean age 37 years, 42 percent female) who had a prior ADHD diagnosis and presented with moderate to severe symptoms (Adult Investigator Symptom Rating Scale [AISRS] score ≥26 and Clinical Global Impression Severity score ≥4). None of the participants had selected current major psychiatric or somatic disorders and were currently using potentially interacting medications.

The participants were randomly assigned to receive either LSD at 20 μg or placebo twice weekly for 6 weeks for a total of 12 doses. The primary outcome was the change in ADHD symptoms from baseline to week 6.

At week 6, the observed changes in AISRS scores did not significantly differ between the LSD and the placebo groups. Specifically, AISRS scores decreased by a mean of 7.1 points (95 percent confidence interval [CI], −10.1 to −4.0) with LSD and by a mean of 8.9 points (95 percent CI, −12.0 to −5.8) with placebo.

In terms of safety, LSD was physically safe and psychologically well tolerated. A total of 124 adverse events (AEs) were documented in the LSD group and 64 in the placebo group. The most common AEs were headache, nausea, fatigue, insomnia, and visual alterations.