A study of 2789 men and 1886 women aged 14 to 85 years old showed a reduced risk of altitude sickness above age 46. The study controlled for age, sex, rate of ascent, final altitude, training status and chemoreceptor responsiveness. Thirty subjects were also evaluated again after a ten year interval.Aging men showed a decreased response to hypoxia with less pronounced desaturation. Men and women had a decreased cardiac response to low oxygen as they aged.

In this article there were numerous citations  of other studies including one that showed an increased risk of severe high altitude illness in endurance athletes.

Jean-Paul Richalet,1,2 and Franc¸ ois J. Lhuissier1,2 High Altitude Medicine and biology June 2015