Cannabis and schizophrenia: a longitudinal study of cases treated in Stockholm County.
By means of the Stockholm County inpatient care register we identified all cases treated with a diagnosis of cannabis dependence and psychosis, not necessarily at the same occasion, during 1971-1983. By scrutinizing medical records, we evaluated the diagnosis according to DSM-III-R and we assessed the history of substance abuse as well as the psychiatric history and clinical course. We identified 229 cases during the follow-up; 112 of these cases (49%) fulfilled the DSM-III-R criteria for schizophrenia. The majority of the schizophrenics had prominent positive symptoms and a sudden onset of disease, and 69% of the cases had a record of heavy cannabis abuse at least 1 year before onset of psychotic symptoms. The high number of verified DSM-III-R cases of schizophrenia in this cohort and the temporal relation between cannabis abuse and schizophrenia further support the hypothesis that cannabis abuse may be a risk factor for schizophrenia. We confirmed previous observations that cannabis-associated schizophrenia often has a sudden onset and prominent positive symptoms.
Allebeck
P
P
Department of Social Medicine, Gothenburg University, Sweden.
Adamsson
C
C
Engström
A
A
Rydberg
U
U
D002188:Cannabis; D005260:Female; D006760:Hospitalization; D006778:Hospitals, Psychiatric; D006801:Humans; D007902:Length of Stay; D008137:Longitudinal Studies; D008297:Male; D011569:Psychiatric Status Rating Scales; D011605:Psychoses, Substance-Induced; D012559:Schizophrenia / Q000175:diagnosis / Q000209:etiology* / Q000534:rehabilitation; D019966:Substance-Related Disorders / Q000150:complications / Q000523:psychology*; D013548:Sweden