CRITICAL REVIEW Coexistence of posttraumatic stress disorder and traumatic brain injury: Towards a resolution of the paradox ALLISON G. HARVEY, 1 CHRIS R. BREWIN, 2 CHARLIE JONES, 1 and MICHAEL D. KOPELMAN 3 1 Department of Experimental Psychology, University of Oxford, Oxford, UK 2 Subdepartment of Clinical Health Psychology, University College London, UK 3 University Department of Psychiatry and Psychology, Guy’s, King’s and St.Thomas’s School of Medicine, Kings College London (Received December 20, 2000; Revised May 13, 2002; Accepted June 29, 2002) Abstract The coexistence of posttraumatic stress disorder (PTSD) and traumatic head or brain injury (TBI) in the same individual has been proposed to be paradoxical. It has been argued that individuals who sustain a TBI and have no conscious memory of their trauma will not experience fear, helplessness and horror during the trauma, nor will they develop reexperiencing symptoms or establish the negative associations that underlie avoidance symptoms. However, single case reports and incidence studies suggest that PTSD can be diagnosed following TBI. We highlight critical issues in assessment, definitions, and research methods, and propose two possible resolutions of the paradox. One resolution focuses on ambiguity in the criteria for diagnosing PTSD. The other involves accepting that TBI patients do experience similar symptoms to other PTSD patients, but that there are crucial differences in symptom content. ( JINS, 2003, 9, 663–676.) Keywords: Posttraumatic stress disorder, Traumatic brain injury, Memory INTRODUCTION A widely held belief is that an individual who has sustained a traumatic brain injury (TBI) during a traumatic event of sufficient severity to involve coma, loss of consciousness, or severe amnesia cannot subsequently develop posttrau- matic stress disorder (PTSD) (e.g., Adler, 1943; O’Brien & Nutt, 1998). The question has also been raised as to whether victims of mild TBI can have PTSD (Boake, 1996; Bontke, 1996; Price, 1994; Trimble, 1981). Similar arguments ap- ply to acute stress disorder (ASD), a condition involving an abnormal short-term psychological response to a traumatic event. Most of the relevant empirical evidence involves vic- tims of motor vehicle (or road traffic) accidents (MVAs) or physical assaults. Whereas some studies of PTSD and TBI have indicated a lack of association (e.g., Mayou et al., 1993; Sbordone & Liter, 1995; Warden et al., 1997), other investigators have reported rates of PTSD in head-injured victims ranging from 20 to 40% (e.g., Bryant & Harvey, 1995; Hickling et al., 1998; Ohry et al., 1996; Rattock & Ross, 1993). This issue of the relationship between PTSD and TBI remains unresolved (McMillan, 1997). This article will begin by describing PTSD, ASD, and TBI, and will discuss related neurological conditions such as retrograde amnesia, postconcussion syndrome and whip- lash injury. We also discuss whether TBI might, theoreti- cally, result in a greater susceptibility to PTSD if important limbic structures are damaged. Then, after presenting the empirical evidence, three theoretical arguments against the dual diagnosis are detailed, and possible resolutions of the paradox outlined. One of our aims is to define impedi- ments to progress in solving the controversy such as poor methods in assessment, confusion in defining terms, and overlap between key terms. Finally, we will discuss a num- ber of clinical and research implications, and identify key questions for future investigations. POSTTRAUMATIC STRESS DISORDER The Diagnostic and Statistical Manual of Mental Dis- orders, Fourth Edition (DSM–IV; American Psychiatric Reprint requests to: Allison Harvey, Department of Experimental Psy- chology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK. E-mail: allison.harvey@psy.ox.ac.uk Journal of the International Neuropsychological Society (2003), 9, 663–676. Copyright © 2003 INS. Published by Cambridge University Press. Printed in the USA. DOI: 10.10170S1355617703940069 663