Classical psychedelic microdosing, mood, and cognitive function: An umbrella review with narrative synthesis.
Level 1 - systematic review of randomized trials
Umbrella review of systematic reviews and meta-analyses
PubMed 42365488 · doi:10.1177/02698811261456196
What was done
This umbrella review with narrative synthesis evaluated systematic reviews and meta-analyses examining microdosing (defined as 20 ug or less of LSD or 3 mg or less of psilocybin per session) on mood and cognitive outcomes in adults. Six databases were searched through February 2026 following JBI guidance and PRISMA 2020 standards (PROSPERO: CRD420251077340). Methodological quality of included reviews was evaluated with AMSTAR-2, and primary-study overlap across reviews was calculated using the corrected covered area (CCA) metric.
What was found
Three meta-analyses met quantitative criteria (synthesizing 14 studies across 13 unique samples, N = 1614), and three additional reviews contributed to narrative synthesis. Primary-study overlap was very high (CCA = 0.29). The only statistically significant pooled effect was a small decrease in cognitive control (d = -0.34, 95% CI: -0.62 to -0.06); all other cognitive domains were non-significant. No eligible meta-analysis provided pooled mood-outcome effect sizes within the microdose threshold, and narrative evidence showed self-reported mood benefits were largely attenuated under placebo-controlled conditions. Short-term tolerability was acceptable, but cardiovascular signals and long-term risks via 5-HT2B activation remain uncharacterized.
Why it matters
This review contradicts popular claims that psychedelic microdosing enhances mood and cognition. Controlled evidence shows no cognitive benefit, a modest impairment in cognitive control, and mood effects that are largely attributable to expectancy bias.
Limits
Primary-study overlap across synthesized reviews was very high (CCA = 0.29), limiting the independence of the evidence base. Quantitative pooling was unavailable for mood outcomes meeting predefined microdose thresholds, requiring reliance on narrative synthesis. Long-term cardiovascular risks related to chronic 5-HT2B receptor stimulation remain unmeasured.
Cited by
- supports Clinical trial evidence to date shows underwhelming efficacy for psychedelic microdosing.