Background: Gulf War I (GWI) veterans continue to report health symptoms many years following their return from the war. The existing research literature on GW-related health problems suggests that one cause is the combined effects of exposure to pesticides and low-level nerve agents (both organophosphates) that work through a similar chemical mechanism affecting the central nervous system (CNS). An ongoing study of military pesticide applicators from GWI classified as high pesticide-exposed reported significantly more health symptoms and performed less well on cognitive testing than their low-exposed GWI veteran counterparts. The proposed follow-up study utilizes structural brain MR imaging in order to investigate CNS pathology and its relationship with health symptoms and cognition in this group of GWI veterans with known pesticide exposures.

Objective/Hypothesis: It is the goal of this study to identify the relationships between organophosphate (OP) pesticides, brain structure, cognitive functioning, and health symptoms in pest-control personnel from the GWI. It is hypothesized that GWI veterans categorized as high pesticide-exposed to specific groups of pesticides (AChE inhibitors) and low-level nerve agents will show lower brain white matter volumes, report more health symptoms, and perform less well on cognitive testing than low-exposed GWI veterans.

Specific Aims: The specific aims of this project are (1) To determine the neuroanatomical and cognitive effects of AChE-inhibiting OP pesticide exposure in specific groups of GWI veterans. (2) To determine the neuroanatomical and cognitive effects of combinations of organophosphates including pesticides and low-level nerve agents (Khamisiyah-exposed) in specific groups of GWI veterans.

Study Design: Military Pest Control Personnel comprise specific groups of GWI veterans likely to fall into high and low categories of pesticide exposure based on their reported pesticide exposures during the war. In addition, low level sarin exposure was determined by Khamisiyah notification. In this study, each participant will undergo a structural brain MRI, a brief cognitive screening battery, and a clinical interview that also identifies psychiatric disorders. They will also complete a health symptom questionnaire and an assessment of environmental exposure since their last evaluation. Veterans with current substance abuse, substantial traumatic brain injury, or metal in their body will be excluded from the study.

Impact: Many GWI veterans still cope with ill-defined symptoms that resemble those found in pesticide exposures. This follow-up brain imaging study will evaluate the combination of exposures to anticholinergic chemicals as factors in the expression of GWI veterans' continued symptoms. Knowledge of these relationships will be useful in identifying objective indicators of pathology that distinguish ill from healthy veterans and for developing plans for prevention of pesticide-induced symptoms among troops deployed in the future.