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Cannabis and schizophrenia: a longitudinal study of cases treated in Stockholm County
Author(s) -
Allebeck P.,
Adamsson C.,
Engström A.
Publication year - 1993
Publication title -
acta psychiatrica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.849
H-Index - 146
eISSN - 1600-0447
pISSN - 0001-690X
DOI - 10.1111/j.1600-0447.1993.tb03408.x
Subject(s) - schizophrenia (object oriented programming) , cannabis , psychiatry , longitudinal study , psychology , medicine , pathology
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.