The Effects of Psilocybin on Social Connectedness

The study is a randomized, double-blind, placebo-controlled, expectancy-controlled, mechanistic trial. This study looks to explore whether a single dose of psilocybin (25mg) reduces amygdala reactivity to negative socioemotional stimuli during the Facial Emotion Recognition Task (FERT) compared to a placebo in adults who feel lonely or those with unresolved grief symptoms.

Inclusion Criteria: * Medically healthy * Ability to provide consent * High loneliness defined by the UCLA-3 Loneliness Scale * Willingness to comply with all study procedures and availability for the duration of the study Exclusion Criteria: * Any unstable medical condition, psychiatric disorder, or circumstance that, in the opinion of the investigator, could compromise participant safety, interfere with study participation, or hinder the participant's ability to comply with study procedures and requirements * Positive pregnancy test or women who are breastfeeding * Any contraindication to MRI such as a pacemaker or metal implants