Chronoecological "glocal" (global and local) health-watch: Men better adapted to ambient hypoxia than women

Background: Gender differences characterize cardiovascular adaptation to high altitude as a halting step toward a spatially (and temporally) "glocal" assessment of cardiovascular function. Spatially glocal differences were previously found in the incidence pattern of sudden cardiac death in different states of the USA and worldwide in Tokyo vs. the Republic of Georgia and Latvia, among others, and were found to change with time in the Czech Republic, documenting the need for glocality in examination in both time and space. A glocal examination of records by the analysis of time series as a whole (globally) and in sections systematically varied in length (locally in time) remains to be initiated in both the circadian and extracircadian domains at high and low altitudes on a larger scale. Human populations adjust to ambient hypoxia via changes in the expression of hypoxia-related genes. In this study, we examine the gender differences in adaptation to high altitude among Indian and Japanese subjects. Methods: We assessed, glocally (globally, to start with in India at high altitude and locally in Japan, in space but not yet glocally in time series), 1,858 Ladakhis (777 men and 1,081 women, aged from 13 to 92 years, average 51.4 years) and 25,211 Japanese (13,366 men and 11,845 women, aged from 16 to 98 years, average 48.0 years).We used validated questionnaires and clinical examination to assess the cardiovascular, autonomic and cognitive functions, at high altitude in Ladakh, India and at low altitude in Japan, comparing men and women in 3 groups living in Ladakh at different altitudes, i.e., from 2,500 to 3,000 meters (m), from 3,200 to 3,720 m, and from 3,800 to 4,590 m above sea level. Aortic stiffness was measured by finding out the cardio-ankle vascular index (CAVI) by the measurements of BP in the right and left forearms and ankles using a VaSera instrument (Fukuda Denshi, Tokyo). Results: As compared to Japanese living at low altitude, highland people in India showed higher values of aortic stiffness of the cardio-ankle vascular index (CAVI) in both men and women. Differences in altitude did not statistically significantly influence BP, pulse oximetry (SpO₂), CAVI, and ECG findings in Ladakhi men. By contrast, CAVI values and BP in sitting position increased with statistical significance with increasing altitude in Ladakhi women. Incidences of first degree AV block, ST depression and abnormal Q waves in the ECG were more frequent at higher altitude in Ladakhi women. The change of SpO2 and diastolic BP over the years were more pronounced in Ladakhi women than in Ladakhi men. Conclusion: Without extrapolating beyond the time and geographic site investigated, women in Ladakh, India, were found to be more sensitive to hypoxia than men who appear to be better adapted.