The Electroencephalogram in Cannabis Associated Psychosis *

Comparison was made among the electroencephalograms of eleven patients with psychotic reactions after the use of cannabis, twenty-nine patients admitted with a diagnosis of schizophrenia, ten for neurological consultations and eleven cannabis users with no apparent psychiatric implications. It was found that there was a greater increase in the EEG abnormalities of cannabis users than in the rest. It is therefore suggested that the drug may be a factor in creating the EEG abnormalities as well as contributing to the psychotic reactions observed, especially when the other factors which could create similar EEG abnormalities have been ruled out.