Psilocybin-Induced Decrease in Amygdala Reactivity Correlates with Enhanced Positive Mood in Healthy Volunteers
Rainer Kraehenmann, Katrin H. Preller, Milan Scheidegger, Thomas Pokorny, Oliver G. Bosch, Erich Seifritz, Franz X. Vollenweider
Biological Psychiatry April 26, 2014 DOI: 10.1016/j.biopsych.2014.04.010 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Double-blind Peer reviewed |
|---|---|
| Sample size | 25 |
| Population | Healthy volunteers |
| Intervention | Psilocybin |
| Dose | 0.16 mg/kg |
| Duration | Two separate sessions at least 14 days apart |
| Topics | Psilocybin Serotonin |
| Keywords | Amygdala Mood Hallucinogen Placebo Reactivity psychology Clinical psychology Receptor |
| Citations | 325 |
| Key findings | Acute psilocybin administration reduced amygdala reactivity to negative stimuli and increased positive mood, with the reduction in right amygdala reactivity linked to the mood improvement. |
Abstract
BackgroundThe amygdala is a key structure in serotonergic emotion-processing circuits. In healthy volunteers, acute administration of the serotonin 1A/2A/2C receptor agonist psilocybin reduces neural responses to negative stimuli and induces mood changes toward positive states. However, it is little-known whether psilocybin reduces amygdala reactivity to negative stimuli and whether any change in amygdala reactivity is related to mood change.MethodsThis study assessed the effects of acute administration of the hallucinogen psilocybin (.16 mg/kg) versus placebo on amygdala reactivity to negative stimuli in 25 healthy volunteers using blood oxygen level-dependent functional magnetic resonance imaging. Mood changes were assessed using the Positive and Negative Affect Schedule and the state portion of the State-Trait Anxiety Inventory. A double-blind, randomized, cross-over design was used with volunteers counterbalanced to receive psilocybin and placebo in two separate sessions at least 14 days apart.ResultsAmygdala reactivity to negative and neutral stimuli was lower after psilocybin administration than after placebo administration. The psilocybin-induced attenuation of right amygdala reactivity in response to negative stimuli was related to the psilocybin-induced increase in positive mood state.ConclusionsThese results demonstrate that acute treatment with psilocybin decreased amygdala reactivity during emotion processing and that this was associated with an increase of positive mood in healthy volunteers. These findings may be relevant to the normalization of amygdala hyperactivity and negative mood states in patients with major depression.