Researchers report they have uncovered remarkable new effects of the potent psychedelic drug lysergic acid diethylamide (LSD) on human cognition, according to findings detailed in a new study.
Published in Psychological Medicine, the study sheds light on LSD’s ability to accelerate learning when coupled with feedback and promote exploratory behavior.
Researchers say the findings may hold the key to unraveling the enigmatic cognitive mechanisms that underlie the potential therapeutic benefits of LSD.
Many recent studies have shown LSD-assisted psychotherapy to offer promising results in treating mental health conditions, including anxiety, depression, and post-traumatic stress disorder.
Though LSD remains illegal in many countries when administered in a controlled setting under the guidance of a trained therapist, the psychedelic drug has shown the potential to enhance individuals’ capacity to explore and process challenging emotions and experiences. Studies have found that this process can often lead to profound insights and lasting breakthroughs in therapy.
Jonathan Kanen, the lead author of the study and a Gates Cambridge Scholar, postulates that the potential therapeutic effects of LSD may stem from the drug’s ability to foster new beneficial patterns of learning about the world by forming new mental associations.
“An important way by which psychedelic drugs, such as LSD, act is through increasing serotonin signals in a unique way, through stimulating the serotonin 2A receptor — this is known to be involved in learning and flexible thinking,” Kanen told PsyPost.
However, research investigating how LSD affects trial-and-error learning in humans has been scarce until now.
Kanen and his team embarked on a quest to investigate the profound effects of LSD on learning and decision-making, with the ultimate aim of unveiling the psychological mechanisms that underlie its potential therapeutic benefits.
To accomplish this, they employed a task called probabilistic reversal learning (PRL), designed to assess participants’ choices under conditions of uncertainty and evaluate their adaptive behavior in response to feedback.
Nineteen volunteers participated in the study, each attending two separate sessions at least two weeks apart.
In each session, a participant was administered either LSD or a placebo, employing a single-blind within-subjects balanced-order design. This design ensured that each participant experienced both LSD and placebo, with the order of administration randomly assigned and counterbalanced across participants.
The participants received a moderate dose of 75 μg of LSD, administered intravenously in a saline solution. Conversely, the placebo was issued in an identical saline solution but contained no LSD.
The PRL task involved presenting volunteers with three visual stimuli, requiring them to choose one.
In the first phase of the task, one stimulus was associated with positive feedback in 75% of trials, another with positive feedback in 50% of trials, and the third with positive feedback in only 25% of trials.
After 40 trials, the probabilities associated with each stimulus were reversed. The once-reliable stimulus, correct 75% of the time, now confounded participants with accuracy only 25% of the time, and so on.
Both classical statistical methods and computational models of reinforcement learning were used to analyze the data. Classical statistics provided insights into how LSD influenced overt choice behavior during the PRL task, while the computational models delved into the underlying learning mechanisms.
Examining the results, researchers discovered that LSD had accelerated the rate at which participants updated their expectations based on feedback. This indicated that individuals under the influence of LSD learned from their experiences far more rapidly than those who received a placebo.
Moreover, the LSD group exhibited a greater inclination toward exploration, actively seeking out new options when making decisions.
The researchers also found that LSD heightened the impact of both positive and negative feedback, with a notable emphasis on learning from rewards rather than punishments.
“LSD enhanced a fundamental learning process,” Kanen explained. “When something better than expected happens to us, the brain updates our expectations or beliefs about whether something good might happen again if we do the same thing. LSD boosted how rapidly expectations are updated, particularly after better than expected outcomes.”
“This indicates that LSD may make the brain more changeable. These results could be relevant to its potential beneficial effects for people with certain mental illnesses.”
Results of the study seem to coincide with previous research, which has offered evidence that LSD promotes brain plasticity, and having a “mystical experience” while on psychedelics could be the key to their therapeutic potential.
Ultimately, the findings suggest LSD’s potential to accelerate learning from feedback and increase exploratory behavior may be what liberate individuals grappling with the confines of negative thought patterns by facilitating the development of new, positive associations.
That said, researchers caution that their recent study only focused on the acute effects of LSD, limiting its scope to the immediate and short-term impact of the drug.
To gain a comprehensive understanding of LSD’s potential, further research must delve into the long-term effects on learning and decision-making, as well as explore the intricate relationship between these effects and therapeutic outcomes.
Additionally, there is the question of if these same positive impacts on learning and exploratory behavior are present in other psychedelic drugs, such as psilocybin.
“An open question is whether these effects of LSD on learning help us understand how to optimize treatments involving psychedelic drugs,” said Kanen. “We studied learning right after administration of LSD — do these effects on learning and flexibility persist after the drug wears off? Whether these effects of LSD generalize to other psychedelic drugs such as psilocybin remains to be tested.”
The study, “Effect of lysergic acid diethylamide (LSD) on reinforcement learning in humans,” was authored by Jonathan W. Kanen, Qiang Luo, Mojtaba Rostami Kandroodi, Rudolf N. Cardinal, Trevor W. Robbins, David J. Nutt, Robin L. Carhart-Harris, and Hanneke E. M. den Ouden.
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: firstname.lastname@example.org or through encrypted email: LtTimMcMillan@protonmail.com