Effects of repeated low-dose LSD on neuropsychological functioning in adults with ADHD: a randomized placebo-controlled study
Psychopharmacology June 20, 2026 E. C. H. M. Haijen-Bongers, P.p.m. Hurks, J. Schepers et al.
In adults with attention-deficit hyperactivity disorder, six weeks of biweekly low-dose lysergic acid diethylamide (20 µg) produced a limited effect on temporal processing, specifically on a time reproduction task, but did not improve performance on other neuropsychological measures of attention, inhibition, or motivational processing. The finding was observed in a secondary analysis of a double-blind, placebo-controlled trial with 46 completers. Baseline performance predicted some treatment outcomes differently between the LSD and placebo groups. The authors caution that the single positive result should be interpreted cautiously, especially because the parent trial showed no corresponding improvements in clinical symptoms.