Study Finds Marijuana Not to Blame for Brain Wave Changes in Psychosis

Researchers examined 93 patients diagnosed with schizophrenia or bipolar disorder, dividing them into recent cannabis users and non-users. EEG readings were compared against 86 healthy control participants with no cannabis use. The study focused on spectral entropy (SE) modulation and connectivity strength (CS) — two measures of brain function that are often disrupted in psychosis.

Both patient groups showed markedly impaired SE modulation and heightened gamma and broadband CS compared to the healthy participants. However, no meaningful differences were observed between cannabis users and non-users within the psychosis group. These findings suggest that the electrophysiological abnormalities typically seen in psychosis are inherent to the disorder, rather than being driven by short-term cannabis use as some have hypothesized. While the study did not explore long-term or early-onset cannabis exposure, the results indicate that recent marijuana consumption is not a major factor behind the EEG disruptions found in psychotic disorders.

The researchers call for further studies to determine whether long-term cannabis use may have a cumulative or delayed effect on brain function in these individuals.