Interrupting the Psychedelic Experience Through Contextual Manipulation to Study Experience Efficacy

Psychedelic therapy research increasingly treats the subjective experience induced by a psychedelic as the therapeutic agent, shifting focus from drug pharmacology to what the authors call “experience efficacy.” Previous work has linked particular experiential qualities — for example feelings of unity, spiritual-type experiences, insightfulness and altered meaning — with therapeutic outcomes, but methods to manipulate those experiences experimentally without changing the drug itself are limited. Roseman and colleagues propose that intentionally interrupting an ongoing psychedelic experience with cognitive tasks could serve as a tool to test experience efficacy. To illustrate this approach, they present a secondary analysis of data from their 2023 DMT study, testing whether increasing in-session cognitive load (operationalised here by asking participants to provide verbal intensity ratings every 60 seconds) attenuates subjective experience and whether such interruptions are associated with smaller improvements in depressive symptoms two weeks later. They hypothesised lower subjective experience ratings under higher task demands and larger reductions in depressive symptoms when task demands were absent during the experience.

This work is reported as a quality improvement study, received ethical approval from the National Research Ethics Committee London‑Brent and the Health Research Authority, and follows the SQUIRE guideline. Healthy volunteers provided informed consent and attended two testing days separated by two weeks. On each testing day participants underwent two intravenous administrations (DMT or placebo) while being scanned with combined functional magnetic resonance imaging and electroencephalography in a randomised order. Each participant completed two scan conditions under the influence of DMT: a “rating” scan, in which they verbally rated subjective intensity of drug effects every 60 seconds in real time while lying with their eyes closed, and a “no rating” scan, in which they rested with eyes closed and did not provide in‑session ratings. Subjective experience was also measured retrospectively after drug effects subsided using the 11 Dimensions Altered States of Consciousness questionnaire (11D‑ASC). Depressive symptoms were assessed with the Quick Inventory of Depressive Symptomatology (QIDS) one day before and two weeks after DMT. To examine the effect of the in‑session interruption, the investigators compared within‑participant total ASC scores between rating and no‑rating scans and conducted exploratory analyses of the 11D‑ASC subfactors. For change in depressive symptoms they minimised potential carryover by analysing only participants’ first DMT session and tested time × group interactions using repeated‑measures analysis of variance. Details of some procedures are reported in a supplement, which was not fully reproduced in the extracted text.

Twenty volunteers were analysed (mean [SD] age 33.5 [7.9] years; 7 female, 35%). Using the total 11D‑ASC score, the investigators found a higher mean (SD) ASC score in the no‑rating condition (0.36 [0.08]) than in the rating condition (0.29 [0.10]); this difference was statistically significant (P < .001, within‑participant paired t test). In exploratory analyses of the 11D‑ASC subfactors, the authors report that not all dimensions differed equally by condition; dimensions previously associated with therapeutic effects (for example unity, spiritual experience, blissful state, insightfulness and changed meaning of percepts) tended to score higher in the no‑rating condition (the paper refers to a figure for these comparisons). To evaluate effects on depressive symptoms while avoiding carryover, only the first DMT session was analysed: 12 participants received DMT first in the rating condition and 8 received DMT first in the no‑rating condition. Repeated‑measures analysis of variance showed a significant group × time interaction (F1,18 = 5.9; P = .03; partial eta squared ηp2 = 0.247), indicating differential change in QIDS scores. The mean (SD) reduction in QIDS two weeks after DMT was larger following the no‑rating session (−1.25 [1.04]) than following the rating session (−0.17 [0.94]) (P = .01). Baseline QIDS scores did not differ significantly between groups (no‑rating 3.12 [1.46] v rating 1.92 [1.78]; P = .12, unpaired t test).

The investigators interpret these secondary‑analysis results as preliminary evidence that contextual manipulation of the psychedelic session — here, interrupting the experience with frequent subjective intensity ratings — can attenuate the reported acute phenomenology and may reduce short‑term improvements in depressive symptoms. They present this approach as a potential experimental tool to probe ‘‘experience efficacy’’ without altering the pharmacological intervention. The authors acknowledge important limitations: the sample was small, the interruption used (verbal ratings every minute) was relatively mild as a cognitive manipulation, and the analysis was secondary to a study not originally designed to test this hypothesis. They therefore recommend that future studies employ more demanding, intentional interruptions to test the concept rigorously. Finally, they suggest that incorporating contextual manipulations into future psychedelic research could help to examine both safety and efficacy, and to clarify the role of particular experiential dimensions in therapeutic outcomes.