BACKGROUND: Few studies have examined samples of people with cannabis-induced psychotic symptoms. AIMS: To establish whether cannabis-induced psychotic disorders are followed by development of persistent psychotic conditions, and the timing of their onset. METHOD: Data on patients treated for cannabis-induced psychotic symptoms between 1994 and 1999 were extracted from the Danish Psychiatric Central Register. Those previously treated for any psychotic symptoms were excluded. The remaining 535 patients were followed for at least 3 years. In a separate analysis, the sample was compared with people referred for schizophrenia-spectrum disorders for the first time, but who had no history of cannabis-induced psychosis. RESULTS: Schizophrenia-spectrum disorders were diagnosed in 44.5% of the sample. New psychotic episodes of any type were diagnosed in 77.2%. Male gender and young age were associated with increased risk. Development of schizophrenia-spectrum disorders was often delayed, and 47.1% of patients received a diagnosis more than a year after seeking treatment for a cannabis-induced psychosis. The patients developed schizophrenia at an earlier age than people in the comparison group (males, 24.6 v. 30.7 years, females, 28.9 v. 33.1 years). CONCLUSIONS: Cannabis-induced psychotic disorders are of great clinical and prognostic importance.
Major depression is a mood disorder that is often accompanied by the impairment of cognitive functions. Although suggestive, the large range of existing neuropsychological, neuropsychiatric, and, lately, neuroimaging investigations have not yet given a consistent picture of the psychological and biological disturbances involved in this psychiatric disorder. The present study of the cognitive functions in depression was part of an extensive investigation, including neuropsychological testing, psychiatric examination, and neuroimaging. A representative sample of 40 severely depressed hospitalized patients and a group of 49 closely matched control subjects were tested with an extensive neuropsychological test battery. Results, corrected for various confounding factors, confirmed the current notion that depressed patients suffer from wide-spread cognitive impairments. The group analysis did not allow any hypothesis on a possible pattern to the dysfunctions, but heterogeneity in the test performances calls for further analysis of the data in patient subgroups in relation to neuroimaging results.