Full length articleAssociations between the self-reported frequency of hearing chemical alarms in theater and regional brain volume in Gulf War Veterans

- Association between hearing chemical alarms and brain volume were examined in Gulf War veterans.
- Cortical GM volume was inversely associated with self-reports of hearing chemical alarms.
- The associations were independent of demographic, clinical, and concurrent GW exposures.
- Cortical GM volume was not significantly associated with predicted Khamisiyah plume exposure.
- There were more Kansas Gulf War Illness cases among veterans who heard chemical alarms in theater.
- Exposure to chemical alarm-triggering substances may have adversely affected veterans brains.

BackgroundWe previously reported evidence of reduced cortical gray matter (GM), white matter (WM), and hippocampal volume in Gulf War (GW) veterans with predicted exposure to low-levels of nerve agent according to the 2000 Khamisiyah plume model analysis. Because there is suggestive evidence that other nerve agent exposures may have occurred during the Gulf War, we examined the association between the self-reported frequency of hearing chemical alarms sound during deployment in the Gulf War and regional brain volume in GW veterans.MethodsNinety consecutive GW veterans (15 female, mean age: 52 ± 8 years) participating in a VA-funded study underwent structural magnetic resonance imaging (MRI) on a 3 T scanner. Freesurfer (version 5.1) was used to obtain regional measures of cortical GM, WM, hippocampal, and insula volume. Multiple linear regression was used to determine the association between the self-reported frequencies of hearing chemical alarms during the Gulf War and regional brain volume.ResultsThere was an inverse association between the self-reported frequency of hearing chemical alarms sound and total cortical GM (adjusted p = 0.007), even after accounting for potentially confounding demographic and clinical variables, the veterans' current health status, and other concurrent deployment-related exposures that were correlated with hearing chemical alarms. Post-hoc analyses extended the inverse relationship between the frequency of hearing chemical alarms to GM volume in the frontal (adjusted p = 0.02), parietal (adjusted p = 0.01), and occipital (adjusted p = 0.001) lobes. In contrast, regional brain volumes were not significantly associated with predicted exposure to the Khamisiyah plume or with Gulf War Illness status defined by the Kansas or Centers for Disease Control and Prevention criteria.ConclusionsMany veterans reported hearing chemical alarms sound during the Gulf War. The current findings suggest that exposure to substances that triggered those chemical alarms during the Gulf War likely had adverse neuroanatomical effects.