LSD enhances suggestibility in healthy volunteers

Authors: RL Carhart-Harris, M Kaelen, MG Whalley, M Bolstridge, A Feilding, DJ Nutt.


About the study

‘Suggestibility’ refers to a person’s susceptibility/responsiveness to the induction of thoughts or actions by others. Suggestibility has been shown to correlate with pain treatment and psychotherapy outcomes, so may be an important mediator of treatment success.

This study measured suggestibility using the Creative Imagination Scale (CIS), which asks participants to imagine scenarios such as their outstretched arm becoming heavier, that they are drinking cool and refreshing water, that they are experiencing anaesthesia in their hand, etc. The intensity of these suggested effects reported by participants is a measure of their ‘imaginative suggestibility.’

In this study, we measured suggestibility twice (on two separate days): once after LSD (40-80µg intravenous) and once after placebo (saline). Before these sessions, participants also completed a self-report questionnaire measuring personality traits.

As expected, we found that LSD enhanced suggestibility. Since enhanced suggestibility can help people interpret or frame their experiences in different ways, this finding supports the idea that LSD could be a valuable supplement to psychotherapy.

An interesting additional finding was that LSD’s suggestibility-enhancing effect correlated with having a conscientious personality – that is, those with the greatest levels of conscientiousness were most sensitive to the suggestibility-enhancing effects of LSD. Since conscientiousness is considered to be related to ‘ego control,’ this supports the idea that LSD temporarily suspends the (very human) drive to maintain control of one’s mind and environment.



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 ?g) 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.

"Suggestibility has been found to play an important role in treatment outcomes for some conditions. For example, hypnotic suggestion is an effective treatment for acute and chronic pain, and there exists an association between the suggestibility and magnitude of clinical effect. Suggestibility may also play a role in psychotherapy outcomes."

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