LSD and language: Decreased structural connectivity, increased semantic similarity, changed vocabulary in healthy individuals.
Isabel Wießner, Marcelo Falchi, Dimitri Daldegan-Bueno, Fernanda Palhano-Fontes, Rodolfo Olivieri, Amanda Feilding, Draulio B Araujo, Sidarta Ribeiro, Natália Bezerra Mota, Luís Fernando Tófoli
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology March 1, 2023 DOI: 10.1016/j.euroneuro.2022.12.013 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized, double-blind, placebo-controlled, crossover study Peer reviewed |
|---|---|
| Sample size | 24 |
| Population | Healthy volunteers |
| Intervention | Lysergic acid diethylamide (LSD) |
| Dose | 50 μg |
| Duration | 24 hours |
| Topics | LSD |
| Keywords | Cognition Natural language processing Semantics Vocabulary Psychedelics hallucinogens Psychoactive drugs Language processing linguistics Speech patterns |
| Citations | 6 |
| Key points | LSD, compared to placebo, changed language structure, decreased semantic distances between words, and altered vocabulary across multiple time points and production types. |
Abstract
Language has been explored as a window into the mind. Psychedelics, known to affect perception and cognition, seem to change language, but a systematic, time-dependent exploration is lacking. Therefore, we aimed at mapping the psychedelic effects on language over the time course of the acute and sub-acute effects in an explorative manner. For this, 24 healthy volunteers (age [mean±SD, range]: 35±11, 25-61 years; 33% women) received 50 μg lysergic acid diethylamide (LSD) or inactive placebo in a randomized, double-blind, placebo-controlled, crossover study. We assessed different language productions (experience reporting, storytelling), components (structure, semantics, vocabulary) and time points (+0 h to +24 h). Language productions included 5-min experience reporting (+1.5 h, +6.5 h) and 1-min storytelling (+0 h, +2 h, +4 h, +6 h, +24 h). Language structure was assessed by computing speech topology (SpeechGraphs), semantics by semantic distances (FastText), vocabulary by word categories (LIWC). LSD, compared to placebo, changed language structure, including decreased verbosity, lexicon, global and local connectivity (+1.5 h to +4 h); decreased semantic distances between neighbouring words and overall words (+2 h to +24 h); and changed vocabulary related to grammar, persons, time, space and biological processes (+1.5 h to +24 h). In conclusion, low to moderate LSD doses changed language over diverse production types, components and time points. While simpler and disconnected structure and semantic similarity might reflect cognitive impairments, changed vocabulary might reflect subjective perceptions. Therefore, language under LSD might provide a window into the psychedelic mind and automated language quantifications should be better explored as valuable tools to yield more unconstrained insights into psychedelic perception and cognition.