The relation between naturalistic use of psychedelics and perception of emotional stimuli: An ERP study comparing non-users and experienced users of classic psychedelics

People who regularly use psychedelic substances in naturalistic settings show reduced early neural responses to negative emotional faces compared to non-users. Electroencephalography measured event-related potentials while participants viewed faces expressing anger, sadness, happiness, or neutrality. Experienced psychedelic users (56 people) had significantly lower N200 amplitudes when processing fearful faces than non-users (55 people), indicating weaker automatic emotional reactivity. Differences also appeared in N170 and N200 components between groups for fearful faces. Later components related to attention (P200, P300) did not differ between groups. Naturalistic psychedelic use may dampen early, automatic processing of negative emotional stimuli.

Study at a glance

Abstract

Previous research indicates that psychedelic substances taken in well-controlled laboratory or therapeutic settings have the potential to decrease negative and increase positive emotional reactivity. However, it is unclear whether similar effects are associated with using psychedelics in less-controlled naturalistic environments. Therefore, in the present study we compared neural markers of emotional stimuli perception between groups of experienced users of psychedelics (N = 56) and non-users (N = 55). EEG signals were collected while participants were presented with pictures of faces showing neutral or emotional expressions (anger, sadness, happiness). Subsequently, we analyzed event-related potential (ERP) components that are established markers of emotional reactivity. Compared to non-users, psychedelics users exhibited weaker neural responses to negative emotional stimuli, as indicated by significantly lower amplitude of the N200 component when processing fearful faces. Furthermore, the analysis revealed significant interaction effects between Group and Emotion on N170 and N200 amplitudes, thus indicating between-group differences in processing of fearful faces. However, analysis of later ERP components associated with attention and cognitive processes (P200, P300) did not reveal significant between-group differences. Therefore, our results indicate that naturalistic use of psychedelics may be related to reduced reactivity to emotionally negative stimuli at the early and automatic processing stages.