OPEN Foundation

M. Kometer

Acute, subacute and long-term subjective effects of psilocybin in healthy humans: a pooled analysis of experimental studies

Abstract

Psilocybin and related hallucinogenic compounds are increasingly used in human research. However, due to limited information about potential subjective side effects, the controlled medical use of these compounds has remained controversial. We therefore analysed acute, short- and longterm subjective effects of psilocybin in healthy humans by pooling raw data from eight double-blind placebo-controlled experimental studies conducted between 1999 and 2008. The analysis included 110 healthy subjects who had received 1–4 oral doses of psilocybin (45–315mg/kg body weight). Although psilocybin dose-dependently induced profound changes in mood, perception, thought and self-experience, most subjects described the experience as pleasurable, enriching and non-threatening. Acute adverse drug reactions, characterized by strong dysphoria and/or anxiety/panic, occurred only in the two highest dose conditions in a relatively small proportion of subjects. All acute adverse drug reactions were successfully managed by providing interpersonal support and did not need psychopharmacological intervention. Follow-up questionnaires indicated no subsequent drug abuse, persisting perception disorders, prolonged psychosis or other long-term impairment of functioning in any of our subjects. The results suggest that the administration of moderate doses of psilocybin to healthy, high-functioning and well-prepared subjects in the context of a carefully monitored research environment is associated with an acceptable level of risk.

Studerus, E., Kometer, M., Hasler, F., & Vollenweider, F. X. (2010). Acute, subacute and long-term subjective effects of psilocybin in healthy humans: a pooled analysis of experimental studies. Journal of Psychopharmacology, 25(11), 1434-1452. http://dx.doi.org/10.1177/0269881110382466
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The neurobiology of psychedelic drugs: implications for the treatment of mood disorders

Abstract

After a pause of nearly 40 years in research into the effects of psychedelic drugs, recent advances in our understanding of the neurobiology of psychedelics, such as lysergic acid diethylamide (LSD), psilocybin and ketamine have led to renewed interest in the clinical potential of psychedelics in the treatment of various psychiatric disorders. Recent behavioural and neuroimaging data show that psychedelics modulate neural circuits that have been implicated in mood and affective disorders, and can reduce the clinical symptoms of these disorders. These findings raise the possibility that research into psychedelics might identify novel therapeutic mechanisms and approaches that are based on glutamate-driven neuroplasticity.

Vollenweider, F. X., & Kometer, M. (2010). The neurobiology of psychedelic drugs: implications for the treatment of mood disorders. Nature Reviews Neuroscience, 11, 642-651. http://dx.doi.org/10.1038/nrn2884
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