Objective: To identify risk factors of factor analysis-derived Gulf War-related syndromes.
Design: A cross-sectional survey.
Participants: A total of 249 Gulf War veterans from the Twenty-fourth Reserve Naval Mobile Construction Battalion.
Data collection: Participants completed standardized booklets measuring self-reported wartime exposures and present symptoms.
Main outcome measures: Associations of factor analysis-derived syndromes with risk factors for chemical interactions that inhibit butyrylcholinesterase and neuropathy target esterase.
Results: Risk of syndrome 1 ("impaired cognition") was greater in veterans who reported wearing flea collars during the war (5 of 20, 25%) than in those who never wore them (7 of 229, 3%; relative risk [RR], 8.7; 95% confidence interval [CI], 3.0-24.7; P<.001). Risk of syndrome 2 ("confusion-ataxia") increased with a scale of advanced adverse effects from pyridostigmine bromide (chi2 for trend, P<.001), was greater among veterans who believed they had been involved in chemical weapons exposure (18 of 108, 17%) than in those who did not (3 of 141, 2%; RR, 7.8; 95% CI, 2.3-25.9; P<.001), and was increased in veterans who had been in a sector of far northeastern Saudi Arabia on the fourth day of the air war (6 of 21, 29%) than in those who had not been (15 of 228, 7%; RR, 4.3; 95% CI, 1.9-10.0; P=.004). Effects of perceived chemical weapons exposure and advanced adverse effects from pyridostigmine were synergistic (Rothman S, 5.3; 95% CI, 1.04-26.7). Risk of syndrome 3 ("arthro-myo-neuropathy") increased with an index of frequency and amount of government-issued insect repellent containing 75% DEET (N,N-diethyl-m-toluamide) in ethanol applied during the war (chi2 for trend, P<.001) and with advanced adverse effects from pyridostigmine (chi2 for trend, P<.001).
Conclusion: Some Gulf War veterans may have delayed, chronic neurotoxic syndromes from wartime exposure to combinations of chemicals that inhibit butyrylcholinesterase and neuropathy target esterase.