CONFIRMED SPEAKERS

Serotonergic psychedelics induce altered states of consciousness, and there is converging evidence that they acutely reduce neuropsychological performance. Unfortunately, little is known about the relationship between the chronic use of these substances and persistent neuropsychological changes. Research with MDMA and cannabis suggests that substances, which alter acute neuropsychological functioning, might also induce impairments after chronic use. Based on this line of research, and studies detailing acute reduction of performance induced by serotonergic psychedelics, we hypothesized that chronic use of these substances is associated with impaired neuropsychological functioning. To test this hypothesis, we conducted a systematic review and meta-analysis, including studies that reported at least one neuropsychological measurement in chronic users of serotonergic psychedelics. I will discuss the detailed results of the studies we included, the overall pattern of neuropsychological functioning we could detect, the results of our meta-analytic calculations, and the conclusions we can draw about persistent neuropsychological changes after chronic use of serotonergic psychedelics. Finally, I will point out which open questions remain, and suggest ways of dealing with methodological hurdles that are common in this type of research. The results of this project are valuable for practitioners, scientists, and everyone else who works with, is interested in, or regularly uses serotonergic psychedelics.