Development and validation of a scale for assessing reasons for substance use in schizophrenia: the ReSUS scale

This paper reports on the development of a questionnaire to assess self reported reasons for substance use in schizophrenia: the 'reasons for substance use in schizophrenia' (ReSUS) scale and explores the relationship between reasons for use, psychiatric symptoms and substance use in a sample of 230 people with psychosis. Principal components analysis revealed three subscales: "coping with distressing emotions and symptoms", "social enhancement and intoxication" and "individual enhancement". Predicted associations were partially supported. 'Coping' reasons for use were related to positive symptoms, general symptoms, global functioning, depression and suicide behaviour as well as substance use (quantity of use and problems related to use). 'Individual enhancement' reasons were related to positive symptoms, to global functioning and to negative consequences of substance use. 'Social enhancement and intoxication' reasons were related to negative consequences of use but not to psychopathology. The findings suggest that the ReSUS is a reliable and valid instrument which can be used to explore self reported reasons for substance use and their relationship to psychotic symptoms in people with schizophrenia and other psychotic disorders.