LSD causes both a ‘glow’ on memory performance and a cognitive ‘hangover’, study finds

LSD appears to cause both improvements and impairments in cognitive function that can be seen the day after consumption, according to a randomized, double-blind, placebo-controlled study published in European Neuropsychopharmacology. The findings shed new light on the lingering cognitive effects of the classic psychedelic.

“Psychedelics primarily impair cognition during their acute effects. However, growing evidence suggests that these substances may have beneficial effects on cognitive function under certain conditions,” said study author Isabel Wießner, a postdoctoral researcher at the Brain Institute of the Federal University of Rio Grande do Norte in Brazil.

“For example, there are laboratory studies showing the potential beneficial effects of microdoses on attention and convergent thinking, as well as neuroplasticity, neurogenesis and neuroprotection. Additionally, studies with participants in psychedelic ceremonies found increases in cognitive flexibility and convergent thinking sub-acutely, in other words, when the acute effects had already worn off (eg, the next morning).

“In light of this, we wanted to systematically investigate the subacute effects of LSD in a methodologically rigorous, placebo-controlled design and see if this substance could demonstrate therapeutic mechanisms beyond the acute effects.”

The study used a crossover design. During a test session, twenty-four healthy volunteers were randomly assigned to receive 50 μg of LSD or an inactive placebo. Two weeks later, the volunteers completed a second test session in which they were assigned to the other condition. Participants had used LSD at least once in their lifetime, but had not used psychedelic drugs in the past two weeks. They also underwent a clinical and psychiatric interview before the study to ensure that they had no relevant medical conditions.

Volunteers completed baseline measurements before ingesting LSD or placebo. About 24 hours later, they returned to the lab to complete a variety of cognitive assessments.

The researchers found that LSD was associated with improved visuospatial memory and improved verbal fluency the next morning. Visuospatial memory is the ability to remember visual information in relation to the environment, while verbal fluency refers to the ability to retrieve words from memory. However, LSD use was also associated with reduced cognitive flexibility, or the ability to quickly switch between different tasks.

“Overall, LSD appears to cause both a ‘glow’ in terms of improved visual memory and verbal fluency, and a ‘hangover’ in terms of impaired cognitive flexibility,” Wießner told PsyPost.

“On the one hand, participants showed increases in visual memory and verbal fluency, so they were better able to learn, consolidate and recall visual input and name words beginning with a particular letter.”

“On the other hand, participants showed significant reductions in cognitive flexibility, as measured by a task in which participants had to learn rules and adapt them according to the changing demands of the task. Although we consider these reductions to be transient and possibly due to exhaustion from the long study before the day, they should be considered transient subacute side effects when using psychedelics in science, therapy, or recreation.”

New research suggests the potential for psychedelics to improve functions related to memory and language. “Therefore, the substance should be further explored as a therapeutic adjunct in conditions involving memory and language impairment, such as stroke, brain injuries and dementia,” Wießner said.

The study, like all research, has some caveats. For example, the dose of LSD was enough to produce psychedelic effects, but it was still relatively low. “Therefore, future studies still need to investigate whether these factors may have influenced the results, including different doses, repeated doses and different post-dose intervals,” explained Wießner.

The study, “LSD, flashback and hangover: Increased episodic memory and verbal fluency, decreased cognitive flexibility,” was authored by Isabel Wießner, Rodolfo Olivieri, Marcelo Falchi, Fernanda Palhano-Fontes, Lucas Oliveira Maia, Amanda Feilding. Arajouio, Dr. , Sidarta Ribeiro and Luís Fernando Tófoli.

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