The emerging science of microdosing: A systematic review of research on low dose psychedelics (1955–2021) and recommendations for the field. (August 2022)

• Record Type: Journal Article
• Authors: Polito, Vince; Liknaitzky, Paul
• Is Part Of: Neuroscience and biobehavioral reviews. Volume 139(2022)
• Publication Date: 2022-08
• Subjects: Microdosing -- Psychedelics -- Hallucinogen -- LSD -- Psilocybin -- Low dose -- Systematic review; Psychophysiology -- Periodicals; Human behavior -- Periodicals; Animal behavior -- Periodicals; Neurology -- Periodicals; Behavior -- Periodicals; Ethology -- Periodicals; Neurology -- Periodicals; Psychophysiologie -- Périodiques; Comportement humain -- Périodiques; Animaux -- Mœurs et comportement -- Périodiques; Neurologie -- Périodiques; Animal behavior; Human behavior; Neurology; Psychophysiology; Periodicals; Electronic journals; 573.8
• DOI: 10.1016/j.neubiorev.2022.104706
• Languages: English
• ISSNs: 0149-7634

Abstract

Abstract: The use of low doses of psychedelic substances (microdosing) is attracting increasing interest. This systematic review summarises all empirical microdosing research to date, including a set of infrequently cited studies that took place prior to prohibition. Specifically, we reviewed 44 studies published between 1955 and 2021, and summarised reported effects across six categories: mood and mental health; wellbeing and attitude; cognition and creativity; personality; changes in conscious state; and neurobiology and physiology. Studies showed a wide range in risk of bias, depending on design, age, and other study characteristics. Laboratory studies found changes in pain perception, time perception, conscious state, and neurophysiology. Self-report studies found changes in cognitive processing and mental health. We review data related to expectation and placebo effects, but argue that claims that microdosing effects are largely due to expectancy are premature and possibly wrong. In addition, we attempt to clarify definitional inconsistencies in the microdosing literature by providing suggested dose ranges across different substances. Finally, we provide specific design suggestions to facilitate more rigorous future research. Highlights: This paper represents the most comprehensive systematic review yet on the widespread practice of microdosing psychedelics. We outline study characteristics, research findings, quality of evidence, and methodological challenges across 44 studies. We found good evidence that psychedelic microdoses can influence pain perception, time perception, and subjective awareness. We found emerging evidence of possible improvements in mental health, substance use disorders, and psychological functioning. We offer a list of recommendations to address limitations and opportunities in the field.