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Cannabis affects the severity of schizophrenic symptoms: results of a clinical survey

  • Juan C. Negrete (a1), Werner P. Knapp (a1), Donald E. Douglas (a1) and W. Bruce Smith (a1)


Data on the history of cannabis use and a spot urine test for cannabinoids were obtained for 137 schizophrenics in treatment. Subjects who were using cannabis during the 6-month observation period presented with a significantly higher degree of delusional and hallucinatory activity than those who did not. Moreover, the group using cannabis made a higher average number of visits to the hospital during the same period. The status of cannabis use appeared to contribute to such variance more than did other relevant factors (age, stage of the illness, amount of medication prescribed, occasional use of other psychoactive substances).


Corresponding author

1Address for correspondence: Professor J. C. Negrete, Department of Psychiatry, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Canada H3G 1A4.


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Cannabis affects the severity of schizophrenic symptoms: results of a clinical survey

  • Juan C. Negrete (a1), Werner P. Knapp (a1), Donald E. Douglas (a1) and W. Bruce Smith (a1)


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