Cannabis psychosis and acute schizophrenia - A case-control study from India

Twenty cases of cannabis psychosis were compared with a control group of 20 patients with 'acute schizophrenic episode' on a number of demographic, cl inical, illness-related and outcome variables in a case-control study desig n using a retrospective chart review, The two groups were comparable on dem ographic, past and family histories of mental illness, premorbid personalit y, psychomotor activity, Schneiderian first-rank symptoms and mild cognitiv e deficits. The cases, in contrast to the control group, had a psychosis of shorter duration characterized by reactive and congruent affect, relative absence of schizophrenic formal thought disorder and a predominantly polymo rphic clinical picture, Relapse was always preceded by cannabis use. This s tudy suggests that, in spite of certain overlaps,'cannabis psychosis' may s till be considered nosologically distinct from schizophrenia in India. The implication of the study is that the role of cannabis in any acute psychosi s should be investigated carefully so as to prevent an over diagnosis of sc hizophrenia.