RecruitingValidating Gulf War Illness Blood BiomarkersThe investigators goals are to identify blood lipids/metabolites that correlate with cognitive decline in the presence of the APOE ε4 allele among veterans with GWI. To determine the effect of dietary, medical and biological factors that influence lipid and metabolites in blood from GW veterans. To identify blood lipid/metabolite profiles that correlate with bioenergetics deficits and glial activation in the brains of GWI. To validate blood biomarker signatures of GWI using APOE genotyping and blood lipids/metabolites that correlate with the CNS dysfunction in GWI.