Simulator sickness among returning combat veterans with mild traumatic brain injury and/or post-traumatic stress disorder

Combat veterans (CV) are experiencing mild traumatic brain injury and/or post traumatic stress disorder (mTBI/PTSD) which may hinder driving performance. Simulators provide a safe environment for testing individuals with impairments, but simulator sickness (SS) may occur and has not been studied in CV. In this retrospective study, we determined the occurrence of SS [total SS (TSS) score from the Simulator Sickness Questionnaire] at baseline, after an initial 5-minute acclimation drive, and after an entire 20-minute drive within and between 21 CV compared to 23 healthy controls (HC). Baseline differences in TSS were significant and were probably due to demographic differences (age and gender) and pre-experimental experience. Susceptibility to SS occurred in CV at two time periods and increased as driving exposure progressed. A significant increase in TSS existed between baseline and after the initial 5-minute acclimation drive in CV [t(-2.59), 8.10, p=0.02] and HC [t(-2.51), 6.41, p=0.02]; and between baseline and after the entire 20-minute drive in CV [t(-3.94), 8.07, p<.01] and HC [t(-4.05), 4.10, p<.01]. A main effect of TSS between groups approached significance (F=2.78, p=0.057) with CV having higher TSS scores than HC. Overall, these findings suggest that CV may have pre-existing conditions that make them more susceptible to SS; and that CV experienced SS more severely compared to HC, every time during the three time periods. Findings must be confirmed in an age and gender matched trial with a larger sample.