The incidence of schizotypy among cannabis and alcohol users.

Abstract

Schizotypy research has revealed associations between positive schizotypal symptomatology and substance use but has not related substance use to important schizotypal traits such as anhedonia. Users and nonusers of cannabis and alcohol completed the Oxford-Liverpool Inventory of Feelings and Experiences, the Peters Delusion Inventory, and the Hospital Anxiety and Depression Scale. Cannabis users scored significantly higher on Unusual Experiences, a scale measuring positive schizotypal symptomatology. Both cannabis and alcohol usage were associated with significantly lower scores on Introvertive Anhedonia, which represents negative symptomatology. Delusional ideation and delusional conviction were significantly higher in cannabis users, but for delusional conviction this was only true for users who also drank alcohol. Neither anxiety or depression scores were higher in cannabis users, but delusional ideation correlated with both anxiety and depression, thus providing mixed support for the idea of the "happy schizotype." Overall, these results suggest that cannabis and alcohol usage is related to different dimensions of psychosis-proneness that broadly parallel the relationship between substance use and positive and negative schizophrenic symptoms, thus supporting the continuity view of psychosis and the multidimensionality of psychosis-proneness.