Renske Erin Blom, PhD cand.

UMC Utrecht

Psychedelic users in The Netherlands, can survey results be used to study the effect of psychedelics on the psyche?



There is a renewed interest in the effect of psychedelics on psychiatric conditions, such as depression and existential distress. Thus far, clinical trials and randomized studies of psychedelics have considered only small numbers of participants, which limits statistical power and our ability to draw firm conclusions. Larger surveys on the effects of psychedelics on mental health of (recreational) users could be informative and cheaper to collect. For survey results to be generalizable we need to assume users and non-users are comparable. To test this hypothesis, we compared their characteristics with non-psychedelic users in the same cohort.


We compared the group of psychedelic users and non-users in terms of gender, age, years of education, use of illicit drugs and alcohol, loneliness, sleep and hallucinations.


Of 6031 participants, 692 (11.5%) had ever used LSD or psilocybin. Psychedelic users had used a wider variety of other drugs (99.0% vs 44.8%,). Similar levels of loneliness were found in non-psychedelic users compared to psychedelic users (mean 2.33 vs. 2.46, p = 0.122) and similar levels of sleep quality and sleep duration.


We found that psychedelic users have tried a significant amount of other illicit drugs. Because almost all illicit drugs have an effect on sleep, emotions and feelings of connectedness/separation and possibly an effect on psychiatric disease, such as depression; this survey research is a less ideal method to study the effect of psychedelics on psychiatric disease. Highlighting the need for randomized and controlled trials.


Renske Blom is a resident psychiatry at the UMC Utrecht/GGZ Centraal and a PhD-candidate. She is involved in the RCT: “the effect of psilocybin on treatment resistant depression”. She worked as a Sub-I in the trial for a year and is currently involved as a chaperone, guiding the RCT-participants during their psilocybin sessions. She is interested in the therapeutic effect of psychedelics.

During her medicine-study, she was involved in the peer-education program (Unity), educating drug users about the effects and side-effects of illicit drugs at dance-parties and festivals and studied the effect of MDMA on hyponatremia in MDMA users at a dance party. She is currently still involved as a physician, advising drug users about the do’s and don’t of illicit drug use in combination with other drugs, medication and psychiatric disease.



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