Microdosing review: no cognitive boost, and a small drop in cognitive control

The question

Does taking very small doses of classical psychedelics, known as microdosing, improve thinking and mental performance?

What they did

Researchers pooled results from 14 studies that tested microdosing of psilocybin or LSD, involving 1,614 people in total. They analyzed 59 separate effect sizes covering several areas of thinking, measured both while the drug was active and on days when it was not. They also checked whether the substance used, the dose, how long people microdosed, or the timing of testing changed the results.

What they found

Overall, microdosing showed no detectable benefit for thinking. There was a significant decrease in cognitive control, the mental ability to stay focused and override automatic responses. No other cognitive domain showed an effect. The type of substance (psilocybin or LSD), the dose (0.1-0.5 g psilocybin; 6.5-20 µg LSD), the length of microdosing (1 to 42 days), and whether testing happened on or off the drug did not change the pattern.

The fine print

The included studies used different methods, tasks and schedules, which makes pooling them difficult. The analysis could not clearly separate short-term drug effects from any lasting change. The finding on cognitive control comes from combining many measures and needs confirmation in studies using standardized protocols. This summary is based on the abstract only.

What it means

Across the controlled evidence available so far, microdosing does not appear to sharpen thinking, and it may slightly weaken the brain’s top-down control processes.

Evidence grade: Moderate. A preregistered meta-analysis pooling 14 controlled studies, but the included studies varied widely in methods and outcomes.

This summary is based on the study’s published abstract.