22 Neuropsychological Outcomes Vary by Sex in Neurotoxicant Exposed Veterans with Gulf War Illness

Abstract

Objective:

More than 30 years after the 199091 Gulf War (GW), approximately 200,000 veterans are still suffering from Gulf War Illness (GWI). Veterans who have this multi-symptom disorder experience impaired cognition, chronic pain, sustained fatigue, and gastrointestinal issues. GWI is believed to be associated with neurotoxicant exposures during the war. Prior research has shown cognitive deficits in combined samples of male and female GW veterans with GWI. These studies have shown that veterans with GWI have cognitive decrements in memory, learning and sustained attention. Studies have yet to compare neuropsychological outcomes by sex. This is mainly due to the lack of collected data on women GW veterans in the past. This study aims to analyze neuropsychological differences in males compared with female veterans with GWI and in those with neurotoxicant exposures from the Boston, Biorepository and Integrative Network (BBRAIN) for GWI repository dataset.

Participants and Methods:

The total sample included 297 veterans with GWI (women n=50, men n=247) who were deployed to the 1990-91 Gulf War with an average age of 52 years. GWI case status was defined by the Kansas GWI criteria. Neuropsychological data including the Conners Continuous Performance Test Third Edition (CPT3), Delis-Kaplan Executive Function System (D-KEFS) Color-Word Interference Test, and the California Verbal Learning Test (CVLT-II) were combined from the BBRAIN repository datasets. War-related exposures, including chemical weapons, anti-nerve gas pills and pesticides were measured by a self-reported survey. Multiple linear regression was used to analyze the association between sex, war-related exposures, and neuropsychological test score outcomes.

Results:

After adjusting for age, education level and PTSD, men had a significantly lower number of words correct in the CVLT-II learning Trials 1-5, short delay recall and long delay recall compared with women veterans (p<0.05). The two groups also differed significantly in CPT3 commission scores, and total time on the D-KEFs Color-Word Inference total times in Trials 1 and 2 with men performing worse (p<0.05). Reported exposure to chemical weapons, pesticides, pyridostigmine bromide (PB) anti-nerve gas pills or smoke from oil well fires were all significantly associated with fewer words correctly recalled on all learning trials of the CVLT-II, long delay, and short delay to a greater degree in men as compared to women (p<0.05). Reported exposure to chemical weapons or smoke from oil well fires were significantly associated with more commission errors on CPT3 in men with GWI (p<0.05). Chemical alarms, smoke from oil well fires and PB were associated with slower response time on the Color-Word Interference test Trial 1 in men compared with women veterans.

Conclusions:

In this study, men with GWI demonstrated significantly poorer performance in verbal memory, learning, response speed and attention. Male veterans reporting neurotoxicant exposures during the war also showed worse learning and verbal memory, impulsivity and response speed decrements compared to exposed women veterans. Future research should consider men and women separately when examining outcomes from war-related exposures.