Disruptions in neural oscillations, particularly in the gamma and theta frequency ranges, are a key mechanism by which THC, the primary psychoactive component of cannabis, perturbs brain function. Clinical EEG studies show that both chronic and acute cannabinoid exposure disrupts these neural oscillations in humans. The authors propose a hypothetical framework where endocannabinoids modulate neural synchrony at the network level, altering the fine tuning of oscillations and the inhibitory/excitatory balance of neural circuits. These oscillatory disruptions may relate to cannabis-induced changes in sensation, perception, and cognition, with implications for disorders such as schizophrenia.
Heavy, chronic cannabis use that begins early and is not accompanied by other drugs is associated with more psychosis-relevant symptoms and poorer cognitive performance. Users averaged over 30,000 lifetime cannabis exposures and scored higher on the Schizotypal Personality Questionnaire (mean 24 vs. 13) and lower on a composite cognitive test (mean -0.23 vs. +0.28) compared to matched non-user controls. Moderate to large deficits appeared in attention, psychomotor speed, working memory, cognitive flexibility, visuo-spatial processing, and verbal memory. A subsample of users also showed worse outcomes than their non-using siblings.