AIMS: This study tested whether adolescents who used cannabis or met criteria for cannabis dependence showed neuropsychological impairment prior to cannabis initiation and neuropsychological decline from before to after cannabis initiation. DESIGN: A longitudinal co-twin control study. SETTING AND PARTICIPANTS: Participants were 1989 twins from the Environmental Risk (E-Risk) Longitudinal Twin...
This chapter updates our knowledge of the short- and long-term effects of cannabis on cognition based on integrating evidence from the most recent literature on this topic. Numerous studies have examined the acute effects of cannabis on human cognition. Cannabis induces perceptual distortions and impairs memory and concentration during acute intoxication. Studies of long-term and heavy cannabis...
BACKGROUND: Controversy remains as to whether cannabis acts as a causal risk factor for schizophrenia or other functional psychotic illnesses. AIMS: To examine critically the evidence that cannabis causes psychosis using established criteria of causality. METHOD: We identified five studies that included a well-defined sample drawn from population-based registers or cohorts and used prospective...