Gender and race as determinants of nausea induced by circular vection.

Background: Within- and between-subject variability of susceptibility for motion sickness is well established, but which factors determine susceptibility is less well known.

Objective: We investigated whether and to what degree sex, race, and head movements contribute to the development of nausea and vomiting (N&V) during pseudorotation in a vection drum in healthy participants.

Methods: Male and female, Chinese and white subjects were exposed to 5x1 minute of circular vection in a conventional rotation drum, with half of the participants performing nausea-enforcing head movements. The symptom ratings (SR) at baseline and after stimulation, the time to perception of illusory self-motion (vection), and the total rotation tolerance (RT) were noted and compared between groups using a 2x2x2 analysis of variance.

Results: A total of 48 healthy young adults (24 Chinese, 24 white; 12 males, 12 females in each group) screened for susceptibility to develop motion sickness participated in this study. SR at baseline and after rotation were significantly lower in Chinese compared with white subjects (for baseline SR: F=20.04, P<0.001; for maximal SR: F=7.09, P=0.011). Vection was equal between both groups, with no effects of gender or head movements. Rotation tolerance was significantly shortened for Chinese compared with white participants (mean [SEM], 216.5 [15.4] sec vs 262.6 [11.3] sec, respectively; F=7.21, P=0.011), with independent influence of head movements (F=8.84, P=0.005) but not of gender.

Conclusions: In this study, the strongest intrinsic factor that contributed to N&V during circular vection was racial origin, whereas sex played a minor role in the degree of N&V under the conditions studied. Head movement-induced vestibular stimulation was a further contributing factor.