Safety and Efficacy of Repeated Low-Dose LSD for ADHD Treatment in Adults: A Randomized Clinical Trial.
Level 2 - randomized trial
Phase 2A double-blind randomized placebo-controlled trial
PubMed 40105807 · doi:10.1001/jamapsychiatry.2025.0044
What was done
A 6-week, multicenter, double-blind, parallel-group phase 2A randomized controlled trial evaluated the safety and efficacy of low-dose LSD for adult ADHD. Fifty-three adults aged 18 to 65 years with moderate-to-severe symptoms (AISRS score ≥26 and CGI-S score ≥4) at centers in Switzerland and the Netherlands were randomized to receive oral LSD (20 µg, n = 27) or placebo (n = 26) twice weekly for 6 weeks (12 doses total). The primary outcome was symptom change from baseline to week 6 measured by the Adult Investigator Symptom Rating Scale (AISRS) using a mixed-effects model for repeated measures.
What was found
Both groups showed symptom improvement from baseline to week 6, but LSD was not superior to placebo. The LSD group had a mean AISRS improvement of -7.1 points (95% CI, -10.1 to -4.0), while the placebo group improved by -8.9 points (95% CI, -12.0 to -5.8), with no significant difference between groups. LSD was reported to be physically safe and psychologically well tolerated.
Why it matters
Despite widespread popular interest in psychedelic microdosing for cognitive enhancement and focus, this trial shows that repeated low-dose LSD is no more effective than placebo for reducing ADHD symptoms in adults.
Limits
The sample size was small (53 participants across two sites). The study tested only a single dose level (20 µg) on a fixed twice-weekly schedule over 6 weeks. The abstract does not report whether blinding integrity was assessed or whether objective cognitive performance measures were evaluated.
Cited by
- supports Clinical trial evidence to date shows underwhelming efficacy for psychedelic microdosing.