IQ differences between patients with first episode psychosis in London and Palermo reflect differences in patterns of cannabis use

Cognitive impairment is a possible indicator of neurodevelopmental impairment, but not all psychotic patients are cognitively compromised. It has been suggested that heavy cannabis use may precipitate psychosis in those who show no such compromise. This study compares two samples of patients with first-episode psychosis and their respective non-psychotic controls, in London (UK) and Palermo (Italy), and examines whether different patterns of...