Addictive Behaviors, Vol. 23, No. 6, pp. 797–812, 1998 Copyright © 1998 Elsevier Science Ltd Printed in the USA. All rights reserved 0306-4603/98 $19.00 + .00 PII S0306-4603(98)00070-7 797 Pergamon FUNCTIONAL ASSOCIATIONS AMONG TRAUMA, PTSD, AND SUBSTANCE-RELATED DISORDERS SHERRY H. STEWART,* ROBERT O. PIHL,† PATRICIA J. CONROD,† and MAURICE DONGIER† *Dalhousie University; and †McGill University Abstract — This review article presents several potential functional pathways which may ex- plain the frequent co-occurrence of PTSD and substance abuse disorders in traumatized indi- viduals. Emerging empirical studies which have examined these potential pathways are re- viewed, including studies on relative order of onset, PTSD patients’ perceptions of various drug effects, comparisons of PTSD patients with and without comorbid substance use disor- ders, and correlational studies examining the relations between severity of specific PTSD symptom clusters and substance disorder symptoms. Research on the acute and chronic ef- fects of alcohol and other drugs on cognitive and physiological variables relevant to PTSD in- trusion and arousal symptoms is reviewed to highlight ways in which these two sets of PTSD symptoms might be functionally interrelated with substance abuse. Finally, based on these findings, recommendations are made for the treatment of individuals with comorbid PTSD- substance use disorders. © 1998 Elsevier Science Ltd Keane, Caddell, Martin, Zimering, and Fairbank (1983) were one of the first research teams to identify high rates of problems with alcohol and other drug abuse, as well as high rates of nicotine and caffeine intake, in treatment-seeking combat veterans with posttraumatic stress disorder (PTSD). Other groups have since reported similarly ele- vated rates of comorbid substance use disorders in clinical samples of veterans with PTSD (e.g., Escobar et al., 1983; Keane, Gerardi, Lyons, & Wolfe, 1988; Keane & Wolfe, 1990; Sierles, Chen, McFarland, & Taylor, 1983; Sierles, Chen, Messing, Be- syner, & Taylor, 1986). In these studies, rates of comorbid alcohol abuse/dependence among PTSD veterans have ranged from 64–84%, and rates of comorbid drug abuse/ dependence have ranged from 40–44%. Population-based field survey studies have confirmed that the high rates of comorbidity between PTSD and substance use disor- ders are not limited to treatment-seeking veterans (e.g., the Vietnam Experience Study, Centers for Disease Control, 1988; the National Vietnam Veterans Readjust- ment Study [NVVRS], Kulka et al., 1988). For example, the NVVRS showed that among veterans with PTSD, substance abuse was by far the most prevalent comorbid disorder; 73% of PTSD veterans also met criteria for a substance abuse disorder (Kulka et al., 1988). Original research presented in this article was supported by a grant from the National Health Research Development Program (NHRDP), Health Canada, awarded to Drs. R. O. Pihl, S. H. Stewart, and M. Dongier. The funded project was conducted through the McGill University–Douglas Hospital Alcohol Research Program, Verdun, Quebec, Canada. The authors acknowledge the research assistance of Heidi Mason, Veronique Fontaine, and Sylvana Cote. We also thank Ken Bruce for his helpful comments on an earlier version of this article. Patricia J. Conrod is currently affiliated with the Cognitive Therapy Unit at the Clarke Institute of Psychiatry, Toronto. Requests for reprints should be sent to Sherry H. Stewart, Department of Psychology, Dalhousie University, Life Sciences Centre, 1355 Oxford Street, Halifax, Nova Scotia B3H 4J1, Canada; E-mail: sstewart@is.dal.ca