Microdosing psychedelics is the practice of consuming very low, sub-hallucinogenic doses of a psychedelic substance, such as lysergic acid diethylamide (LSD) or psilocybin-containing mushrooms. According to media reports, microdosing has grown in popularity, yet the scientific literature contains minimal research on this practice. There has been limited reporting on adverse events associated with microdosing, and the experiences of microdosers in community samples have not been categorized. In the present study, we develop a codebook of microdosing benefits and challenges (MDBC) based on the qualitative reports of a real-world sample of 278 microdosers. We describe novel findings, both in terms of beneficial outcomes, such as improved mood (26.6%) and focus (14.8%), and in terms of challenging outcomes, such as physiological discomfort (18.0%) and increased anxiety (6.7%). We also show parallels between benefits and drawbacks and discuss the implications of these results. We probe for substance-dependent differences, finding that psilocybin-only users report the benefits of microdosing were more important than other users report. These mixed-methods results help summarize and frame the experiences reported by an active microdosing community as high-potential avenues for future scientific research. The MDBC taxonomy reported here informs future research, leveraging participant reports to distil the highest-potential intervention targets so research funding can be efficiently allocated. Microdosing research complements the full-dose literature as clinical treatments are developed and neuropharmacological mechanisms are sought. This framework aims to inform researchers and clinicians as experimental microdosing research begins in earnest in the years to come.

The purpose of this study was to evaluate the effects of repetitive transcranial magnetic stimulation (rTMS) on suicidal ideation in patients with treatment-resistant major depression (TRD) (patients who failed to clinically respond to at least 2 medication trials). We pooled data from 2 published prospective randomized controlled trials of rTMS applied to the dorsolateral prefrontal cortex in patients with TRD. We compared the effect of bilateral, left unilateral, and sham rTMS on suicidal ideation as measured by the suicide item of the 17-item Hamilton Depression Rating Scale (HDRS) (N = 156). Suicidal ideation resolved in 40.4%, 26.8%, and 18.8% of participants randomized to bilateral, left unilateral, and sham rTMS, respectively. The difference between bilateral and sham was significant (OR = 3.03; 95% CI, 1.19-7.71; P = .02), unlike the difference between left unilateral and sham (OR = 1.59; 95% CI, 0.61-4.12; P = .33). There was a modest correlation between change in suicidal ideation and change in depression severity (Pearson r = 0.38; P < .001) and no difference in change of HDRS-16 score between suicide remitters and nonremitters (P = .32). Bilateral rTMS was superior to sham rTMS in reducing suicidal ideation in patients with TRD. Only a small portion of the reduction in suicidal ideation was attributable to the reduction in depressive symptoms. These data suggest that suicidal ideation could be a specific target symptom construct for rTMS. ClinicalTrials.gov identifiers: NCT01515215 and NCT00305045.

Psychedelic therapy shows promise for a range of mental health concerns, including suicidality. This meta-analysis is the first to systematically examine the effects of psychedelic therapy on suicidality.

Introduction: Effective blinding is especially challenging in randomized controlled trials (RCTs) involving psychedelics due to the inherent alterations in consciousness that these compounds induce. In this systematic review and exploratory analysis, we aim at synthesizing the methodologies used in RCTs involving classic psychedelics and identify procedures that can help minimize unblinding and bias. Methods: We completed a literature search that included prospective RCTs published between 1963 and January 2023, in which participants were randomized to receive either a classic psychedelic or placebo. Results: A total of 1402 papers were included in the initial search. After eligibility criteria were applied, 50 papers from 48 clinical trials were included. Most studies were double blinded ( n = 34), used a within-subjects design ( n = 32 studies), and included inert placebos ( n = 35). The majority of studies did not report on the integrity of blinding procedures ( n = 34 studies); however, in studies that did, blinding was unsuccessful. Conclusion: To improve blinding and lower expectancy effects, we suggest incorporating active placebos and utilizing dose response or active comparator study designs.