Annu. Rev. Clin. Psychol. 2006. 2:161–97 doi: 10.1146/annurev.clinpsy.2.022305.095305 Copyright c  2006 by Annual Reviews. All rights reserved P OSTTRAUMATIC STRESS DISORDER: Etiology, Epidemiology, and Treatment Outcome Terence M. Keane, Amy D. Marshall, and Casey T. Taft VA Boston Healthcare System, Boston University School of Medicine, Boston, Massachusetts 02130; email: Terry.Keane@va.gov, Amy.Marshall2@va.gov, Casey.Taft@va.gov Key Words trauma, prevalence, risk factors, intervention, psychopharmacology ■ Abstract Posttraumatic stress disorder (PTSD) results from exposure to a trau- matic event that poses actual or threatened death or injury and produces intense fear, helplessness, or horror. U.S. population surveys reveal lifetime PTSD prevalence rates of 7% to 8%. Potential reasons for varying prevalence rates across gender, cultures, and samples exposed to different traumas are discussed. Drawing upon a conditioning model of PTSD, we review risk factors for PTSD, including pre-existing individual- based factors, features of the traumatic event, and posttrauma social support. Charac- teristics of the trauma, particularly peritraumatic response and related cognitions, and posttrauma social support appear to confer the greatest risk for PTSD. Further work is needed to disentangle the interrelationships among these factors and elucidate the underlying mechanisms. Based upon existing treatment outcome studies, we recom- mend use of exposure therapies and anxiety management training as first-line treatment for PTSD. Among psychopharmacological treatments, selective serotonin reuptake in- hibitors evidence the strongest treatment effects, yet these effects are modest compared with psychological treatments. CONTENTS HISTORY AND BACKGROUND ........................................ 162 PREVALENCE AND COURSE ......................................... 163 Posttraumatic Stress Disorder in the United States Population ................ 163 Posttraumatic Stress Disorder Among United States Combatants .............. 165 Posttraumatic Stress Disorder Across the Globe ........................... 166 Posttraumatic Stress Disorder Among Refugees ........................... 167 Posttraumatic Stress Disorder Following Disasters ......................... 168 A CONDITIONING MODEL OF THE ETIOLOGY OF POSTTRAUMATIC STRESS DISORDER ............................. 168 RISK FACTORS FOR POSTTRAUMATIC STRESS DISORDER .............. 169 Pre-existing Factors ................................................. 170 The Traumatic Event Itself ............................................ 174 Trauma Severity .................................................... 174 1548-5943/06/0427-0161$20.00 161 Annu. Rev. Clin. Psychol. 2006.2:161-197. Downloaded from arjournals.annualreviews.org by University of Wisconsin - Madison on 03/29/06. For personal use only.