LSD, afterglow and hangover: Increased episodic memory and verbal fluency, decreased cognitive flexibility

This trial (n=24) investigated the effects LSD (50 μg) has on a number of measures of cognition in healthy volunteers. It was found that LSD sub-acutely improved visuospatial memory, phonological verbal fluency and impaired cognitive flexibility when compared to placebo suggesting that LSD-assisted therapy may provide a novel treatment in conditions involving memory and language declines.


“Psychedelics acutely impair cognitive functions, but these impairments decline with growing experiences with psychedelics and microdoses may even exert opposing effects. Given the recent evidence that psychedelics induce neuroplasticity, this explorative study aimed at investigating the potential of psychedelics to sub-acutely change cognition. For this, we applied a randomized, double-blind, placebo-controlled, crossover study with 24 healthy volunteers receiving 50 μg lysergic acid diethylamide (LSD) or an inactive placebo. Sub-acute changes in cognition were measured 24 h after dosing, including memory (Rey-Osterrieth Complex Figure, ROCF; 2D Object-Location Memory Task, OLMT; Rey Auditory-Verbal Learning Test, RAVLT), verbal fluency (phonological; semantic; switch), design fluency (basic; filter; switch), cognitive flexibility (Wisconsin Card Sorting Test, WCST), sustained and switching attention (Trail Making Test, TMT), inhibitory control (Stroop Task) and perceptual reasoning (Block Design Test, BDT). The results show that when compared to placebo and corrected for Body Mass Index (BMI) and abstinence period from psychedelics, LSD sub-acutely improved visuospatial memory (ROCF immediate recall points and percentage, OLMT consolidation percentage) and phonological verbal fluency and impaired cognitive flexibility (WCST: fewer categories achieved; more perseveration, errors and conceptual level responses). In conclusion, the low dose of LSD moderately induced both “afterglow” and “hangover”. The improvements in visuospatial memory and phonological fluency suggest that LSD-assisted therapy should be explored as a novel treatment perspective in conditions involving memory and language declines such as brain injury, stroke or dementia.”

Authors: Isabel Wießner, Rodolfo Olivieri, Marcelo Falchi, Fernanda Palhano-Fontes, Lucas O. Maia, Amanda Feilding, Draulio B. Araujo, Sidarta Ribeiro & Luís Fernando Tófoli

Study details

Compounds studied

Topics studied
Neuroscience Healthy Subjects

Study characteristics
Placebo-Controlled Double-Blind Re-analysis

24 Humans


Authors associated with this publication with profiles on Blossom

Luís Tófoli
Luís Tófoli is a professor at UNICAMP and one of the organizers of ICARO, his work is mostly done in Brazil and focused on ayahuasca.

Amanda Feilding
Amanda is the Founder and Director of the Beckley Foundation. She's called the 'hidden hand' behind the renaissance of psychedelic science, and her contribution to global drug policy reform has also been pivotal and widely acknowledged.

Compound Details

The psychedelics given at which dose and how many times

LSD 50 μg | 1x