Turn on, Tune in, and Drop out: Predictors of Attrition in a Prospective Observational Cohort Study on Psychedelic Use

This post-hoc survey study (n=654) sought to identify factors accounting for the high attrition rates in a prospective study on naturalistic psychedelic use and found that the strongest predictors for participant dropping out were among demographic variables including age, educational levels, and personality traits, but unrelated to psychedelic-specific factors such as challenging experiences or prior dispositions towards psychedelics. These results partially address concerns over sampling biases results due to high drop-out rates and conclude that future psychedelic research can improve participation through conventional incentives, such as remuneration, gamification, or by forming web-based participant communities.


Background: The resurgence of research and public interest in the positive psychological effects of psychedelics, together with advancements in digital data collection techniques, have brought forth a new type of research design, which involves prospectively gathering large-scale naturalistic data from psychedelic users; that is, before and after the use of a psychedelic compound. A methodological limitation of such studies is their high attrition rate, particularly owing to participants who stop responding after initial study enrollment. Importantly, study dropout can introduce systematic biases that may affect the interpretability of results.

Objective: Based on a previously collected sample (baseline n=654), here we investigated potential determinants of study attrition in web-based prospective studies on psychedelic use.

Methods: Logistic regression models were used to examine demographic, psychological trait and state, and psychedelic-specific predictors of dropout. Predictors were assessed 1 week before, 1 day after, and 2 weeks after psychedelic use, with attrition being defined as noncompletion of the key endpoint 4 weeks post experience.

Results: Predictors of attrition were found among demographic variables including age (β=0.024; P=.007) and educational levels, as well as personality traits, specifically conscientiousness (β=-0.079; P=.02) and extraversion (β=0.082; P=.01). Contrary to prior hypotheses, neither baseline attitudes toward psychedelics nor the intensity of acute challenging experiences were predictive of dropout.

Conclusions: The baseline predictors of attrition identified here are consistent with those reported in longitudinal studies in other scientific disciplines, suggesting their transdisciplinary relevance. Moreover, the lack of an association between attrition and psychedelic advocacy or negative drug experiences in our sample contextualizes concerns about problematic biases in these and related data.”

Authors: Sebastian Hübner, Eline Haijen, Mendel Kaelen, Robin Lester Carhart-Harris & Hannes Kettner

Summary of Turn on, Tune in, and Drop out: Predictors of Attrition in a Prospective Observational Cohort Study on Psychedelic Use


Psychedelic substances have likely been consumed by humans for thousands of years through different species of plant and fungi. A resurgence of studies into the psychological and neural effects of psychedelic substances is now being paralleled by commercial and policy developments.

The use of psychedelics is becoming increasingly widespread, and digital data collection techniques have made it possible to gather large-scale longitudinal data sets from psychedelic users by using prospective study designs. However, there are also significant limitations, including the lack of experimental controls, participant accountability, and data validity.

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Study details

Topics studied

Study characteristics
Observational Longitudinal Survey



Authors associated with this publication with profiles on Blossom

Robin Carhart-Harris
Dr. Robin Carhart-Harris is the Founding Director of the Neuroscape Psychedelics Division at UCSF. Previously he led the Psychedelic group at Imperial College London.

Mendel Kaelen
Mendel Kaelen is a neuroscientist and entrepreneur, researching and developing a new category of psychotherapeutic tools for care-seekers and care-providers. Mendel has researched the incomparable effects of music on the brain during LSD-assisted psychotherapy. His work has determined how LSD increases enhanced eyes-closed visual imagery, including imagery of an autobiographical nature. This gives light to how music can be used as another dimension in helping psychotherapists create the ideal setting for their patients.


Institutes associated with this publication

Imperial College London
The Centre for Psychedelic Research studies the action (in the brain) and clinical use of psychedelics, with a focus on depression.

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