Evidence map›Paper›PMID 42322409›Full record

ArticlePsychopharmacology2026

Effects of repeated low-dose LSD on neuropsychological functioning in adults with ADHD: a randomized placebo-controlled study.

E C H M Haijen-Bongers, P P M Hurks, J Schepers, P Vizeli, J Santos de Jesus, L Mueller, Y Schmid, M E Liechti, K P C Kuypers

Registry-linked trialAbstract read
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In one paragraph

Article in Psychopharmacology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT05200936 (Safety and Efficacy of Repeated Low Dose d-Lysergic Acid Diethylamide), which is not on this map. Not yet cited in PubMed.

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1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

NCT05200936 phase2completednot on this map

Safety and Efficacy of Repeated Low Dose d-Lysergic Acid Diethylamide (LSD) D-tartrate (MM120) as Treatment for ADHD in Adults: a Multi-center, Randomized, Double-blind, Placebo-controlled Phase 2a Proof of Concept Trial

TypeinterventionalSponsorDefinium Therapeutics US, Inc.Ran2021 to 2023Enrolled53ConditionsADHD, Attention Deficit DisorderArmsMM120, Placebo
3 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

9 authors.

E C H M Haijen-BongersDepartment of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands. e.haijen@maastrichtuniversity.nl.
P P M HurksDepartment of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands.
J SchepersDepartment of Methodology and Statistics, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands.
P VizeliDivision of Clinical Pharmacology and Toxicology, Department of Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland.
J Santos de JesusDivision of Clinical Pharmacology and Toxicology, Department of Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland.
L MuellerDivision of Clinical Pharmacology and Toxicology, Department of Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland.
Y SchmidDivision of Clinical Pharmacology and Toxicology, Department of Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland.
M E LiechtiDivision of Clinical Pharmacology and Toxicology, Department of Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland.
K P C KuypersDepartment of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

rationaleAttention-deficit hyperactivity disorder (ADHD) shows substantial heterogeneity in symptoms and cognitive deficits. According to the Triple Pathway Model, this variability may stem from impairments in three neuropsychological domains: inhibition, motivation, and temporal processing. Repeated low-dose administration of psychedelics is being explored as a treatment for ADHD, but evidence from controlled studies in this population remains limited.

objectivesThis study investigated performance across neuropsychological domains relevant to ADHD: attention, inhibition, motivational processing, and temporal processing, before and after a six-week biweekly low-dose lysergic acid diethylamide (LSD) treatment (20 µg) in adults with ADHD. Based on previous findings, we expected improvements in attention and temporal processing and explored whether baseline ADHD symptoms and domain-specific task performance predicted treatment outcomes.

methodsThis study presents a secondary analysis of a double-blind, placebo-controlled, parallel group trial. Performance on objective behavioral tasks was assessed at baseline and after six weeks of treatment, before intake of the final dose.

resultsFifty-three patients were randomized to LSD (n = 27) or placebo (n = 26), and 46 completed the study (LSD: n = 23; placebo: n = 23). An effect of LSD was observed on temporal processing (Time Reproduction Task), leaving performance on other tasks unaffected. Exploratory analyses indicated that baseline performance differentially predicted outcomes related to inhibition and time reproduction in the LSD and placebo groups.

conclusionsThese findings do not provide convincing evidence for broad cumulative benefits of low-dose LSD treatment across neuropsychological domains in adults with ADHD. The observed effect was limited to a single time reproduction measure and should be interpreted cautiously, particularly given the absence of corresponding improvements in clinical symptoms in the parent trial. Future studies should investigate the robustness of this finding and whether effects are acute, cumulative, or subgroup-specific. REGISTRY: ClinicalTrials.gov, TRN: NCT05200936, Registration date: 21 December 2021.

Indexed as

Adult attention-deficit hyperactivity disorderLow dosesLSD treatmentNeuropsychological functioningPlacebo-controlled trialTriple Pathway Model

Identifiers

PMID42322409

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.