A systematic study of microdosing psychedelics
Vince Polito, Richard J. Stevenson
PLoS ONE, 2019, 14, (2), e0211023.
Doi : 10.1371/journal.pone.0211023
The phenomenon of ‘microdosing’, that is, regular ingestion of very small quantities of psychedelic substances, has seen a rapid explosion of popularity in recent years. Individuals who microdose report minimal acute effects from these substances yet claim a range of long-term general health and wellbeing benefits. There have been no published empirical studies of microdosing and the current legal and bureaucratic climate makes direct empirical investigation of the effects of psychedelics difficult. In Study One we conducted a systematic, observational investigation of individuals who microdose. We tracked the experiences of 98 microdosing participants, who provided daily ratings of psychological functioning over a six week period. 63 of these additionally completed a battery of psychometric measures tapping mood, attention, wellbeing, mystical experiences, personality, creativity, and sense of agency, at baseline and at completion of the study. Analyses of daily ratings revealed a general increase in reported psychological functioning across all measures on dosing days but limited evidence of residual effects on following days. Analyses of pre and post study measures revealed reductions in reported levels of depression and stress; lower levels of distractibility; increased absorption; and increased neuroticism. To better understand these findings, in Study Two we investigated pre-existing beliefs and expectations about the effects of microdosing in a sample of 263 naïve and experienced microdosers, so as to gauge expectancy bias. All participants believed that microdosing would have large and wide-ranging benefits in contrast to the limited outcomes reported by actual microdosers. Notably, the effects believed most likely to change were unrelated to the observed pattern of reported outcomes. The current results suggest that dose controlled empirical research on the impacts of microdosing on mental health and attentional capabilities are needed.
Microdosing refers to the practice of ingesting a very low dose of a psychedelic substance . There has been little peer-reviewed research on microdosing but there are numerous blogs and online communities that discuss the practice, with detailed guides to methods and anecdotal reports of outcomes (e.g., www.microdosing.com; www.reddit.com/microdosing/wiki). Typical doses can be as small as one twentieth of a typical recreational dose, sometimes even less . So, for example, a microdose of lysergic acid diethylamide (LSD) might be 6–25 micrograms, or a microdose of psilocybin might be .1 to .5 grams of dried mushrooms . People microdose using a wide range of different substances, although LSD and psilocybin are the most commonly discussed in online forums .
Psychedelics have typically been associated with marked alterations in cognition, affect, perception, and neurophysiology . Individuals who have taken psychedelics typically describe pronounced changes in visual and auditory perception, accompanied by vivid imaginative experiences and intense emotions. This is not the case with microdosing. Microdosing is frequently described as involving a ‘sub-threshold’ dose . That is, individuals aim to identify a dose at which they do not feel ‘high’. In other words, when microdosing there are only minimal identifiable acute drug effects.
People follow a variety of different schedules when microdosing, sometimes taking a dose each day but much more frequently interspersing dosing days with rest days. One common schedule is to microdose every three days . The idea behind this regimen is that there may be a residual effect from each microdose that lasts one to two days afterwards. Most popular press stories on microdosing have mentioned this three day cycle [8,9].
Despite the reported lack of acute effects of microdosing, proponents claim a wide variety of psychological and social benefits from regular microdosing, including increases in vitality, creativity, productivity, social ability, focus, analytic thinking, positive mood, memory, mindfulness and general wellbeing . Microdosing is thus a curious phenomenon: on the one hand advocates deny experiencing the alterations in consciousness that characterise typical doses, yet claim significant psychological benefits from regular use.
The earliest occurrence of microdosing is unknown. Anthropological reports indicate that many traditional cultures incorporated use of psychedelic plants such as peyote, morning glory seeds and psilocybin containing mushrooms into many aspects of daily life . These substances were used as a catalyst for ritual religious experience , but also used at lower doses as an aphrodisiac, to reduce hunger, inspire courage, nullify pain, and to treat ailments such as gout and syphilis . These uses highlight that although psychedelics are now commonly associated with marked alterations in consciousness, they also have also been used historically at low doses for therapeutic benefits and functional enhancement.
The modern practice of microdosing is quite a recent phenomenon. Albert Hofman, the discover of LSD, mentioned the use of very low doses of LSD (25 micrograms) in passing during in a 1976 interview  but we have not been able to identify any other records from Dr Hofman or his contemporaries describing microdosing. Stanislav Grof developed psycholytic psychotherapy  as a form of psychedelic assisted therapy that involved small amounts of LSD, but the lower range for doses was over 100 micrograms—considerably higher than contemporary microdosing. There was no formal research on microdosing prior to the prohibition of psychedelic research in 1966.
The current popularity of microdosing can be traced back to a book, The Psychedelic Explorers Guide by James Fadiman . This was the first publication to describe microdosing in detail. Fadiman outlined the purported benefits of regular microdosing, with a recommendation to follow a three-day cycle, and guidelines for appropriate doses. This publication also contained a collection of case reports from individuals about their microdosing experiences, emphasising positive improvements in creativity, focus, affect, and relationships. In the years following this publication, a number of news articles appeared reporting on the growing interest in microdosing. The first major publication to report on the phenomenon was Rolling Stone . This article triggered considerable popular media interest in microdosing psychedelics that has led to over 1200 news articles on the topic since that time. Many stories in the popular press have focused on microdosing as tool for increased productivity, particularly for people working in the technology sector [17–19]. This sudden high level of almost exclusively positive news coverage has been accompanied by the emergence of multiple communities of microdosers on social media. For example, a forum on microdosing on reddit.com has over 24,000 members who report on their experiences and compare notes on methodologies, outcomes and protocols. The comprehensive news coverage and active online communities of microdosers have led to a situation where large numbers of individuals are experimenting with microdosing, with the expectation that this practice leads to substantial psychological and wellbeing benefits.
To date there are four scientific articles on microdosing. Three of these indicate potential benefits from microdosing. First, Johnstad  conducted a series of interviews with microdosers, who reported generally positive outcomes, including improved mood, energy levels and cognition. Second, in an open label study, Prochazkova et al.  found that microdosing led to increases in convergent and divergent thinking–common indicators of creativity. Third, a large cross sectional study found that microdosers reported reduced levels of negative attitudes and emotions, and increased wisdom, open-mindedness and creativity, relative to people who had never microdosed . Fourth, the most scientifically rigorous study to date, was a double blind placebo controlled study by Yanakieva et al. . This study showed changes in time perception following microdosing, but did not investigate variables related to health or wellbeing.
In addition to this formal research, microdosers’ expectations are likely based on informal case reports, anecdotes, unpublished studies, and online publications [3,24–26]. Although microdosing is understudied, its sudden popular interest has occurred within a context of growing scientific attention on the effects of psychedelics taken at higher doses . After a long period of minimal research with psychedelic compounds as a result of government prohibitions, an increasing number of research teams have in recent years reported compelling findings suggesting both improved psychological functioning  and potential therapeutic benefits  associated with a range of psychedelic substances.
When administered to healthy individuals in a supportive setting, both psilocybin [30–33] and LSD , have been shown to elicit mystical-type experiences that are characterised as highly meaningful and transformative by participants. In the case of psilocybin, Griffiths et al.  reported persisting self and observer rated positive effects on attitudes, mood and behaviour 14 months after ingestion, with 58% of participants reporting that their psilocybin experience was among the five most personally meaningful experiences of their lives. Psilocybin  and LSD  have also both been shown to bias emotional processing toward positive information and to attenuate responses to fearful stimuli. In addition psilocybin has been shown to increase emotional empathy , whereas LSD has been shown to increase feelings of wellbeing, closeness to others and trust ; increase emotional response and personal meaningfulness to music [39,40]; and increase suggestibility .
In more clinically oriented research, both psilocybin and LSD have shown promise as treatments for end of life anxiety. In a double blind, randomised crossover trial of psilocybin assisted psychotherapy as a treatment of anxiety and depression in terminal cancer patients, Griffiths et al.  found remission in both depressive and anxious symptoms for over 60% of patients at 6 month follow up. A similar trial of LSD assisted psychotherapy by Gasser, Kirchner and Passie  found significant reductions in state and trait anxiety that were maintained at 12-month follow up. Psilocybin has also been shown to reduce the symptoms of treatment resistant depression , and to dramatically reduce consumption levels when trialled as a treatment for tobacco addition [45,46], and alcohol dependence .