[Effects of simulated high altitude hypoxia on cognitive performance]

To investigate the effects of mild and moderate hypoxia on human cognitive performance.

Eighteen healthy young male volunteers performed a set of tests of human ergonomics at sea level (300 m in Xi'an) and simulated high altitude of 2 800 m, 3 600 m and 4 400 m for 1 h in hypobaric chamber, respectively.

The performance of continuous recognition memory tests compared with the controls' was deteriorated significantly (P < 0.01) after exposure to 2 800 m for 1 h. After exposure to 3 600 m for 1 h, in all test, the reaction time was much longer, the accurate rates were lower and the performance was worse than that of control (P < 0.05). All the parameters were deteriorated with the increment of altitude and the performance of all tests were much worse at 4 300 m for 1 h (P < 0.01).

Different parameters of human cognitive performance may have different susceptible thresholds to hypoxia according to the results from our studies. The cognitive performance after exposure to 3 600 m for 1 h was not sufficiently effective for the demands of human ergonomics due to its significant deteriorating changes. However, the performance can be effectively restored after exposure to enough oxygen supply for 1 h.