There is a large proportion of individuals experiencing simulator sickness symptoms (headaches, nausea, paleness, etc.). Previous studies have reported that driving in a simulator, compared to on-road driving, can alter braking responses while stopping at intersections. Here we evaluated whether altered braking responses observed in fixed-base simulators could be linked to the presence of sickness symptoms in older drivers. Older individuals participated in a 5-session training study that included a pre-test, three training sessions and a post-test. We evaluated adaptation to simulator sickness through repeated exposure (5 simulator sessions). Furthermore, we assessed whether head postural instability accounted for the presence of sickness symptoms. Sickness symptoms were measured with the Simulator Sickness Questionnaire (SSQ) and a Visual Analog Scale (VAS). After the first session, half of the participants reported mild symptoms (MS, VAS score>5), and another half reported light symptoms (LS, VAS score<5). We compared sickness symptoms, braking responses and head postural stability between the two groups for the first (pre-test) and last (post-test) driving sessions. During the pre-test, participants of the MS group braked earlier, showed longer time of deceleration, a greater number of pedal activations and showed increased irregularities in their deceleration profile. Participants from the MS group adapted in that, sickness symptoms reduced through exposure. During the post-test, we observed a larger decrease in variability for the MS than the LS group, but we did not find any difference regarding the braking responses per se or the head postural stability. We interpreted these results as evidence that adaptation is accompanied with a reduction of variability. Finally, we propose that a more gradual exposure to simulated environment might be required before evaluating the driving performance of individuals prone to simulator sickness
