The emerging science of microdosing: A systematic review of research on low dose psychedelics (1955 – 2021)
December 15, 2021 preprint DOI: 10.31234/osf.io/edhqz via OpenAlex
Summary
A systematic review of 44 studies on microdosing psychedelic substances from 1955 to 2021 indicates varying effects on mood, cognition, and mental health. Laboratory studies reported changes in pain and time perception, while self-report studies noted alterations in cognitive processing. The review challenges the notion that microdosing effects are primarily due to expectancy and highlights definitional inconsistencies in the literature. Recommendations for improving future research design are also provided.
Study at a glance
| Design | systematic review |
|---|---|
| Sample size | 44 |
| Population | empirical microdosing research studies published between 1955 and 2021 |
| Key finding | The review finds that claims regarding microdosing effects being largely due to expectancy are premature and possibly incorrect. |
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.