1991 2007g-416 biomedicalresearch braininjuries combat combatdisorders diseases etiology healthandhygiene healthaspects medicalcare mentalhealth middleeast persiangulfsyndrome persiangulfwar physiologicalaspects post-traumatic post-traumaticstressdisorder psychologicalaspects psychology qz140 qz140u58g2009 research stressdisorders unitedstates veterans wm184w2532007