Acute psilocybin effects on CBF and ICA diameter
OpenAlex – January 01, 2026
Source: OpenAlex
Summary
Psilocybin dramatically reduces cerebral blood flow, with magnetic resonance imaging revealing widespread cortical reductions in 28 healthy participants. Psilocybin (0.2–0.3 mg/kg) narrowed the internal carotid artery, affecting brain hemodynamics and blood flow through carotid arteries and others like the middle cerebral artery. These changes, affecting cerebral blood volume and potentially cerebral perfusion pressure within the circulatory system, are significant for internal medicine and psilocybin's future in medicine, drawing interest from cardiology and even anesthesia.
Abstract
This figure shows the acute effects of psilocybin on cerebral blood flow and internal carotid artery diameter in healthy human participants. Whole-brain cerebral blood flow was measured using pseudo-continuous arterial spin labelling MRI at baseline, during the peak and late phases following psilocybin administration (0.2–0.3 mg/kg, N = 28). Cerebral blood flow maps illustrate widespread cortical reductions at peak plasma psilocin levels. Plasma psilocin concentrations were negatively associated with both whole-brain cerebral blood flow and internal carotid artery diameter, indicating dose-dependent effects. MRI acquisition, preprocessing, and statistical modelling procedures are described in detail in Larsen et al. (Journal of Cerebral Blood Flow & Metabolism, 2025).