A further complicating issue in the differential diagnosis between PTSD and TBI is the range of other comorbid problems that commonly coexist with both TBI and PTSD. For example, depression is highly prevalent with both conditions. Numerous studies have suggested that TBI increases the risk for developing depression,29,30 eg, refs 31,32,33. Some of the core symptoms noted across TBI and PTSD are also seen in depression, especially the more severe forms of TBI, including concentration problems, memory problems, irritability, reduced motivation,

and fatigue. Highlighting this problem in one study was a finding that more than 50% of depressed Inhibitors,research,lifescience,medical patients met symptom criteria for moderate/severe postconcussive Inhibitors,research,lifescience,medical syndrome.34 This contributes to the conclusion that some of the symptoms attributed to TBI may in fact be generic symptoms of psychological malaise, which are observed across anxiety and depressive responses. Complicating the issue of comorbidity is

compounded by the fact that TBI, PTSD, and depression commonly occur in the context of chronic pain, which Inhibitors,research,lifescience,medical also results in symptoms that overlap with each of these conditions.35-41 Prevalence PTSD and TBI are not uncommon. Epidemiological studies indicate that most people in the community have been exposed to traumatic stressors,42,43 although anly a minority develop PTSD. For example, the National Comorbidity Survey found that 21 % of the women and 8% of the men had developed PTSD.42 Similarly, a Detroit study found that 13% of the women and 6% of the men had developed PTSD.43 That is, although men are more likely to be exposed to trauma than women, women have at least a twofold risk of developing PTSD compared with men. 44 More severe Inhibitors,research,lifescience,medical traumas tend to result in more severe PTSD. Interpersonal violence Inhibitors,research,lifescience,medical leads to

more PTSD than impersonal trauma; for example, whereas 55% of rape victims develop PTSD, only 7.5% of accident victims develop PTSD:42,45 In terms of TBI, there are between 1.5 and 2 million people in the USA alone who sustain a TBI, with approximately 70 000 to 90 000 experiencing persistent functional difficulties.46 The Centers for Disease Control and Prevention estimates that approximately 5.3 million people in the USA are living with a disability due to TBI.47 Batimastat Certain populations appear to be more at risk of sustaining TBIs. For example, military estimates of mild TBI of deployed (non-mcdically evacuated) CHIR99021 personnel indicate that between 10% and 20% may have suffered a mild TBI during deployment.48 One study reported a rate as high as 23% in personnel assessed after returning to the USA.49 Can PTSD develop following TBI? Some earlier commentators argued that PTSD could not develop following TBI because the impaired consciousness at the time of trauma precluded encoding of the traumatic experience, and this prevented trauma memories that are necessary for PTSD development.50,51 In contrast, evidence has accumulated that PTSD can develop following mild TBI.