Sub-acute effects of psilocybin on EEG correlates of neural plasticity in major depression: Relationship to symptoms
Jordan Sloshower, Hamideh Safi-Aghdam, Surbhi Pathania, Brian Pittman, Patrick D. Skosnik, Shariful A. Syed, Deepak Cyril D’souza
Journal of Psychopharmacology June 30, 2023 DOI: 10.1177/02698811231179800 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Double-blind, placebo-controlled, within-subject study Peer reviewed |
|---|---|
| Sample size | 19 |
| Population | Individuals with major depressive disorder |
| Intervention | Psilocybin |
| Dose | 0.3 mg/kg |
| Duration | 2-week follow-up after each session |
| Topics | Neuroplasticity Psilocybin Depression |
| Keywords | Electroencephalography Antidepressant Placebo Hallucinogen Anesthesia |
| Citations | 47 |
| Key points | Psilocybin increased EEG theta power two weeks after a single dose, and this increase correlated with improvements in depression symptoms. |
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.