Mentioned in Niel's link to Frontline's Interview Lt. Gen. Eric B. Schoomaker are a couple of links. Very generally, a series of RAND studies are found at the Invisible Wounds of War webpage.
More specifically and to the point is the Fort Carson EPICON (epidemiological consultation) Report.
The upfront conclusions in this 126 page report are at pages ES-2 through ES-4.
Regards
Mike
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