Delta-9-tetrahydrocannabinol, neural oscillations above 20 Hz and induced acute psychosis
Judith F. Nottage, James M. Stone, Robin M. Murray, Alexander Luke Sumich, Elvira Bramon, Dominic H Ffytche, Paul D. Morrison
Psychopharmacology July 19, 2014 DOI: 10.1007/s00213-014-3684-1 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Double-blind crossover study Peer reviewed |
|---|---|
| Sample size | 15 |
| Population | Healthy participants given intravenous THC or placebo (13 crossover pairs plus 4 THC-only for resting EEG; 15 for the motor task) |
| Intervention | delta-9-tetrahydrocannabinol (THC) |
| Measures | Positive and Negative Syndrome Scale (PANSS) |
| Topics | Cannabis |
| Citations | 34 |
| Key points | Intravenous THC shifted resting EEG toward higher frequencies, reducing 21-27 Hz and increasing 27-45 Hz magnitude, and this effect correlated with PANSS positive symptoms (r = 0.429). THC also increased 65-130 Hz event-related synchronization over contralateral sensorimotor areas, driven by the 85-130 Hz band. The authors propose this faster-gamma shift may reflect cortical over-activation possibly related to saliency misattribution in delusions. |
Abstract
Rationale: An acute challenge with delta-9-tetrahydrocannabinol (THC) can induce psychotic symptoms including delusions. High electroencephalography (EEG) frequencies, above 20 Hz, have previously been implicated in psychosis and schizophrenia.
Objectives: The objective of this study is to determine the effect of intravenous THC compared to placebo on high-frequency EEG.
Methods: A double-blind cross-over study design was used. In the resting state, the high-beta to low-gamma magnitude (21-45 Hz) was investigated (n = 13 pairs + 4 THC only). Also, the event-related synchronisation (ERS) of motor-associated high gamma was studied using a self-paced button press task (n = 15).
Results: In the resting state, there was a significant condition × frequency interaction (p = 0.00017), consisting of a shift towards higher frequencies under THC conditions (reduced high beta [21-27 Hz] and increased low gamma [27-45 Hz]). There was also a condition × frequency × location interaction (p = 0.006), such that the reduction in 21-27-Hz magnitude tended to be more prominent in anterior regions, whilst posterior areas tended to show greater 27-45-Hz increases. This effect was correlated with positive symptoms, as assessed on the Positive and Negative Syndrome Scale (PANSS) (r = 0.429, p = 0.042). In the motor task, there was a main effect of THC to increase 65-130-Hz ERS (p = 0.035) over contra-lateral sensorimotor areas, which was driven by increased magnitude in the higher, 85-130-Hz band (p = 0.02) and not the 65-85-Hz band.
Conclusions: The THC-induced shift to faster gamma oscillations may represent an over-activation of the cortex, possibly related to saliency misattribution in the delusional state.