Trauma exposure rather than posttraumatic stress disorder is associated with reduced baseline plasma neuropeptide-Y levels

Background: Exposure to uncontrollable stress reduces baseline plasma neuropeptide-Y levels in animals. We previously reported that baseline plasma neuropeptide-Y levels, as well as neuropeptide-Y responses to yohimbine, were lower in combat veterans with posttraumatic stress disorder, but we were unable to determine whether this was attributable to posttraumatic stress disorder or trauma exposure. The current report addresses this issue. Methods: A) Baseline plasma neuropeptide-Y levels were measured in 8 healthy combat veterans compared to 18 combat veterans with posttraumatic stress disorder and 8 healthy nontraumatized subjects; and B) Baseline plasma neuropeptide-Y levels, trauma exposure, and posttraumatic stress disorder symptoms were assessed in 41 active military personnel. Results: Plasma neuropeptide-Y was negatively associated with trauma exposure but not posttraumatic stress disorder symptoms in active duty personnel. Baseline neuropeptide-Y was reduced in combat veterans with and without posttraumatic stress disorder. Conclusions: Trauma exposure rather than posttraumatic stress disorder is associated with reduced baseline plasma neuropeptide-Y levels. Future studies must determine if neuropeptide-Y reactivity differentiates trauma-exposed individuals with and without posttraumatic stress disorder. Biol Psychiatry 2003;54:1087-1091 (C) 2003 Society of Biological Psychiatry