LSD enhances suggestibility in healthy volunteers

This within-subjects, placebo-controlled study (n=10) found that the influence of suggestion is enhanced by LSD, especially in individuals with high trait ‘conscientiousness’, which may have implications for the use of LSD in psychotherapy.

Abstract

“Rationale: Lysergic acid diethylamide (LSD) has a history of use as a psychotherapeutic aid in the treatment of mood disorders and addiction, and it was also explored as an enhancer of mind control.

Objectives: The present study sought to test the effect of LSD on suggestibility in a modern research study.

Methods: Ten healthy volunteers were administered with intravenous (i.v.) LSD (40–80 μg) in a within-subject placebo-controlled design. Suggestibility and cued mental imagery were assessed using the Creative Imagination Scale (CIS) and a mental imagery test (MIT). CIS and MIT items were split into two versions (A and B), balanced for ‘efficacy’ (i.e. A≈B) and counterbalanced across conditions (i.e. 50 % completed version ‘A’ under LSD). The MIT and CIS were issued 110 and 140 min, respectively, post-infusion, corresponding with the peak drug effects.

Results: Volunteers gave significantly higher ratings for the CIS (p = 0.018), but not the MIT (p = 0.11), after LSD than placebo. The magnitude of suggestibility enhancement under LSD was positively correlated with trait conscientiousness measured at baseline (p = 0.0005).

Conclusions: These results imply that the influence of suggestion is enhanced by LSD. Enhanced suggestibility under LSD may have implications for its use as an adjunct to psychotherapy, where suggestibility plays a major role. That cued imagery was unaffected by LSD implies that suggestions must be of a sufficient duration and level of detail to be enhanced by the drug. The results also imply that individuals with high trait conscientiousness are especially sensitive to the suggestibility-enhancing effects of LSD.”

Authors: Robin L. Carhart-Harris, Mendel Kaelen, Matthew G. Whalley, Mark Bolstridge, Amanda Feilding & David J. Nutt