The proposed research builds on a Merit Review Award to Dr. Vasterling, "Follow-up of Psychological and Neurocognitive Gulf War Outcome: Relation to Stress," which is a longitudinal, case-controlled study of psychological functioning in over 800 deployed and 250 nondeployed GW-era veterans. Variables currently examined include self-reported health symptoms, psychological symptoms, and individual difference variables (e.g., personality characteristics), stress exposure, self-reported environmental hazards exposures, and objective neurocognitive data (on a subset of veterans). This pilot study extends the "Follow-up" study by introducing a distinct set of variables related to olfactory functioning.