Sub-acute effects of psilocybin on EEG correlates of neural plasticity in major depression: Relationship to symptoms
Journal of Psychopharmacology – June 30, 2023
Source: OpenAlex
Summary
A single psilocybin dose doubled specific brain activity linked to neuroplasticity, measured via Electroencephalography (EEG), in 19 individuals with depression. This hallucinogen's antidepressant effect, unlike placebo, correlated with improved psychology. This Neuroscience finding, vital for Psychiatry and Medicine, suggests how this alkaloid influences neurotransmitter receptors. While distinct from anesthesia, these Psychedelics and Drug Studies highlight chemical synthesis's role in advancing our understanding of behavior.
Abstract
Background: Evidence suggests that serotonergic psychedelics (e.g. psilocybin), have rapid-acting and long-lasting antidepressant effects after a single dose. However, the mechanism underlying these effects remain unclear. One proposed mechanism is that these drugs promote neuroplasticity. However, this has not been conclusively demonstrated in humans. Aims: We hypothesized that relative to placebo, psilocybin would: (1) increase electroencephalographic (EEG) correlates of neuroplasticity, (2) reduce depression symptoms, and (3) changes in EEG would correlate with improvements in depression. Methods: In this double-blind, placebo-controlled, within-subject study, individuals with major depressive disorder (MDD; n = 19) were administered placebo followed by psilocybin (0.3 mg/kg) in a fixed order (placebo, followed by psilocybin 4 weeks later). EEG indices of neuroplasticity (tetanus-induced long-term potentiation) as assessed via auditory evoked theta (4–8 Hz) power and measures of depression (GRID Hamilton Rating Scale for Depression-17 (GRID-HAM-D-17)) were measured at several time-points after placebo and psilocybin (24 h and 2 weeks after each session). Results: EEG theta power doubled in amplitude 2 weeks after a single psychedelic dose of psilocybin but not after placebo. Further, improvements in depression symptoms 2 weeks after psilocybin were correlated with increases in theta power. Conclusions: The increased theta power observed represents evidence of sustained changes in the brain following psilocybin. Given the correlation with enhancement in depressive symptoms, changes in theta may represent an EEG biomarker of the sustained effects of psilocybin, and may shed light on potential mechanisms of psilocybin’s antidepressant effect. Taken together, these results complement the emerging notion that psilocybin, and perhaps other psychedelics, can produce long-term alterations in neuroplasticity.