Consequences of cannabis use in schizophrenia patients

Previous research has shown that the ability to organize information for remembering in an intentional and strategic way is impaired in schizophrenia patients (Rizzo et al., 1996) and that the remembering is accompanied by a low level of autonoetic awareness (Danion et al., 1999). Chronic and heavy uses of cannabis induce cognitive impairments. These impairments persist while the user remains intoxicated, and may or may not be reversible after prolonged abstinence from cannabis (Lundqvist, 2005). The aim of the present study was to investigate whether past cannabis use may reduce more subtle deficits in neurocognitive functioning such as deficit of the specificity of autobiographical memories and the associated level of autonoetic awareness in a population of schizophrenia patients.
The TEMPau (Piolino, 2000) was used to evaluate the autobiographic memory and the level of autonoetic consciousness. Participants were asked to generate 3 specific memories for four life periods (0-9 years old, 10-19 years old, after 20 years old and the last 12 months). Performances from 6 past cannabis use schizophrenia patients were compared to performances of 8 schizophrenia patients no users. Patients were not treated with benzodiazepines.
The analysis revealed a significant group difference for the 10-19 years old period for the specificity of autobiographical memories ( t2,11 = 2.3 ; p = 0.041). Past cannabis users reported less specific events (m = 6.83 (1.94)) compared to the no users patients (m = 9.14 (1.67)). The implications of this result will be discussed.