Psychedelic Information Theory

Shamanism in the Age of Reason


Acute psychological and physiological effects of psilocybin in healthy humans: a double-blind, placebo-controlled dose-effect study

Hasler F, Grimberg U, Benz M, Huber T, Vollenweider F; Psychopharmacology, Volume 172, Number 2 / March, 2004

Rationale Serotonin (5-Hydroxytryptamine, 5-HT) receptors play an important role in perception, affect regulation and attention. Pharmacological challenge with the 5-HT2A agonist psilocybin (PY) is useful in studying the neurobiological basis of cognition and consciousness. Objective Investigation of dose-dependent effects of PY on psycho(patho)logical and physiological parameters.

Methods Eight subjects received placebo (PL), and 45 (ldquovery low dose, VLDrdquo), 115 (ldquolow dose, LDrdquo), 215 (ldquomedium dose, MDrdquo), and 315 (ldquohigh dose, HDrdquo) mgrg/kg body weight PY. The ldquoAltered States of Consciousness Rating Scalerdquo (5D-ASC), the ldquoFrankfurt Attention Inventoryrdquo (FAIR), and the ldquoAdjective Mood Rating Scalerdquo (AMRS) were used to assess the effects of PY on psycho(patho)logical core dimensions, attention, and mood. A 24-h electrocardiogram (EKG) was recorded and blood pressure was measured. Plasma concentrations of thyroid-stimulating hormone (TSH), prolactin (PRL), cortisol (CORT), adrenocorticotropic hormone (ACTH), and standard clinical chemical parameters were determined.

Results PY dose dependently increased scores of all 5D-ASC core dimensions. Only one subject reacted with transient anxiety to HD PY. Compared with PL, MD and HD PY led to a 50% reduction of performance in the FAIR test. ldquoGeneral inactivationrdquo, ldquoemotional excitabilityrdquo, and ldquodreaminessrdquo were the only domains of the AMRS showing increased scores following MD and HD PY. The mean arterial blood pressure (MAP) was moderately elevated only 60 min following administration of HD PY. Neither EKG nor body temperature was affected by any dose of PY. TSH, ACTH, and CORT plasma levels were elevated during peak effects of HD PY, whereas PRL plasma levels were increased following MD and HD PY.

Conclusion PY affects core dimensions of altered states of consciousness and physiological parameters in a dose-dependent manner. Our study provided no cause for concern that PY is hazardous with respect to somatic health.

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