A 12-month prospective follow-up study of patients with schizophrenia-spectrum disorders and substance abuse Changes in psychiatric symptoms and substance use Howard C. Margolese a,b,d , Juan Carlos Negrete a,d , Raymond Tempier c,d , Kathryn Gill a,d, * a Addictions Unit, McGill University Health Centre, Canada b Clinical Psychopharmacology Unit, McGill University Health Centre, Canada c Continuing Care Service, McGill University Health Centre, Canada d Department of Psychiatry, McGill University, Montreal, Quebec, Canada Received 19 July 2005; received in revised form 17 November 2005; accepted 18 November 2005 Available online 7 February 2006 Abstract While it is widely known that patients with schizophrenia-spectrum psychoses and co-occurring substance us more difficult to manage, there is limited data on the course of their psychiatric symptoms when they remain in time.This prospective 12-month study evaluated changes in psychiatric symptoms and substance use to ascert existence of substance use disorders influences ratings of psychiatric symptoms at follow-up. 147 outpatients in a continuing care program were assessed at intake and followed prospectively for 12 mon symptoms were measured at baseline and 12-month follow-up using the Positive and Negative Syndrome Scale Hamilton Depression Rating Scale (HAM-D). Subjective psychological distress was rated with the Brief Symptom Inven (BSI) and quality of life by the Satisfaction with Life Domains Scale (SDLS). Drug and alcohol use was measured with the Addiction Severity Index (ASI). 50.3% of patients were diagnosed with dual disorders (DD) (current and lifetime). The most common primar abuse were alcohol (35.6%) and cannabis (35.1%). DD subjects had higher baseline PANSS positive scores but greater reduction at 12 months compared to single diagnosis (SD) patients. Severity of substance abuse as measured by ASI composite scores did not decrease significantly between baseline and 12 months. DD patients with schizophrenia and related psychoses treated for their psychiatric illness showed a reduction scores over 12 months, even when their substance use remained largely unchanged. However, co-morbidity ca 0920-9964/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2005.11.019 * Corresponding author. Addictions Unit, Montreal General Hospital, 1604 Pine Avenue West, Montreal, Quebec, Canada H3G 514 934 8311; fax: +1 514 934 8262. E-mail address: kathryn.gill@mcgill.ca (K. Gill). Schizophrenia Research 83 (2006) 65 – 75 www.elsevier.com/locate/schres