Mild traumatic brain injury and posttraumatic stress disorder: clinical and conceptual complexities.

The wars in Iraq and Afghanistan have raised public con-sciousness of traumatic brain injury (TBI) and posttraumaticstress disorder (PTSD), two of the most common healthconsequences of contemporary military deployment. TBI andPTSD may each in their own right exert a toll on affectedindividuals. Within the war zone, however, brain injury oftenoccurs within a broader context of extreme psychologicalstress (i.e., traumatic stress). Th e same dangerous circumstances(e.g., combat, encounters with improvised explosive devices)that lead to increased risk of TBI also place service membersat increased risk for PTSD. Therefore, the prevalence ofPTSD in returning war-zone veterans who have a history ofdeployment-related TBI are elevated, especially when thebrain injury falls at the milder end of the severity range,as is the case with the majority of deployment-relatedTBIs. For example, a RAND study estimated that almost20% of a representative sample of Operation EnduringFreedom/Operation Iraqi Freedom veterans screened positivefor history of mild TBI (mTBI), and that of those reportinga deployment mTBI, approximately 34% also screenedpositive for PTSD (Tanielian & Jaycox, 2008).The comorbidity of mTBI and PTSD is not limited, however,to war-zone veterans. Civilian events such as motor vehicleaccidents and interpersonal ass ault may also be associated withboth TBI and psychological traum a sufﬁciently severe to lead toPTSD. The prevalence of comorbid mTBI and PTSD is notwell-documented in civilians, but mTBI and/or PTSD eachaffect many civilians. The Centers for Disease Control andPrevention (2010) estimate that over 1.7 million people sustaina TBI each year, and that over 75% of these injuries are mild.A U.S. population-based survey estimated the prevalenceof PTSD in the general population to be at 7–8% (Kessler,Sonnega, Bromet, Hughes, & Nelson, 1995).Despite the relatively high rates of mTBI and PTSD inat-risk populations, much remains unknown about the clinicalconsequences in individuals who have both incurred anmTBI and experience PTSD. The sequelae of mTBI are oftenreferred to as post traumatic or post concussive symptoms.Some post traumatic symptoms (e.g., irritability, neurocog-nitive complaints) overlap with PTSD symptoms, makingdifferential diagnosis difﬁcult. Other conditions commonlyco-occurring with TBI history and PTSD, such as chronicpain, depression, and substance abuse, may further complicatethe clinical presentation of patients with both history of mTBIand PTSD. As a result, considerablechallengesarise inregardsto both the assessment and clinical management of patientswith co-morbid mTBI and PTSD.The ﬁeld of neuropsychology is well-positioned to tacklemany of the clinical and conceptual challenges posed bycomorbid mTBI and PTSD. This virtual special issue of theJournal of the International Neuropsychological Society (JINS)compiles eight papers on the topic of TBI and/or PTSD thatwere previously published in regular issues of JINS. The papersare for the ﬁrst time grouped together with the goal of collec-tively addressing the issues con fronting clinicians who assessand care for patients with history of mTBI and PTSD.