Translated from our German original by AI. The German text was researched, written, and edited by the Psychedelia Foundation team and remains the authoritative version.
LSD, DMT, and psilocybin can change various cognitive and psychological functions. The effects differ, however, depending on the function, the dose, and the timing of the assessment. That is the finding of a systematic review that analyzed 32 placebo-controlled studies from 1990 to 2025.
For reaction time, attention, and the control of automatic responses in particular, the authors frequently found impairments during the acute effect. In many studies these were dose-dependent. Some studies, however, found no such changes.
Memory yields no uniform picture either. Depending on the task used and the timing of the assessment, impairments, improvements, and no change at all were all observed.
Interesting differences emerged for empathy. The psychedelics tended to increase emotional empathy, meaning the emotional resonance with other people. For cognitive empathy, the ability to understand another person’s perspective or mental state, the authors found no comparable effect.
Some studies also suggested that participants recognized negative emotional stimuli less well under the acute effect. Results on cognitive flexibility, the ability to switch between modes of thinking and acting, were contradictory.
The strength of the evidence is limited, however. Many of the included studies had small samples. Reliable blinding against placebo is also difficult with psychedelics, because the subjective effects are often clearly noticeable to participants. The authors therefore call for larger studies and, in particular, for more research on longer-term effects.
The review thus provides no evidence of a general improvement in cognitive performance through psychedelics. Rather, LSD, DMT, and psilocybin show a differentiated pattern of effects: certain cognitive functions can be impaired during the acute effect, while emotional processing, and emotional empathy in particular, changes at the same time.
