Abstract
AIMS: This article argues that despite a resurgence in research on psychedelics over the last two decades, we still have little insight into the psychedelics user population. Furthermore, there is currently little agreement between researchers as to the long-term mental health consequences of psychedelics use. DESIGN: In a methodological review of a range of studies in psychedelics use, it is demonstrated that these studies tend to focus on specific segments of the user population while excluding others. These population segments are probably connected to different patterns of use, which in turn are likely to result in different long-term consequences. RESULTS: The divergent findings on the consequences of psychedelics use may be explained, at least in part, by the fact that different research strategies explore different segments of the user population. Studies focusing on user segments with problematic usage patterns tend to find that psychedelics use is negative for mental health, while studies on infrequent users tend to find that psychedelics use is positive for mental health. CONCLUSION: Because the field of psychedelics studies lacks a reliable model of the user population, it is difficult for researchers to contextualise and assess the broader validity of their findings. To remedy this situation, the article presents three theoretical models of the user population that afford us with tentative means of contextualising findings and thereby may clarify present disagreements.