[Association between high altitude and depression in the Himalayas and the Andes]

Suicide rates in the United States are higher in higher altitude areas, and hypoxia has been cited as a factor in these higher rates. There may be a significant correlation between rates of depression and altitude, but little data exist outside the United States. The purpose of the present study is to conduct a survey of depression among the elderly residing in the Himalayas and the Andes.

We visited Ladakh (altitude 3,800-4,800 m) in India, Qinghai (3,700 m) in China and Puyca (3,600 m) in Peru between July 2009 and July 2011. We recruited 114 farmers from Domkhar in Ladakh (mean age, 69.2 years; female-male ratio, 58.8%), 206 nomads from Changthang in Ladakh (55.1 years; 43.7%), 173 Tibetan subjects from Qinghai (66.5 years; 61.3%) and 103 indigenous Andean subjects from Puyca (69.0 years; 68.0%). The two-item Patient Health Questionnaire (PHQ-2) was administered to the subjects. A psychiatrist interviewed the residents with single or double positive scores on the PHQ-2.

The ratio of subjects with one or more positive score in PHQ-2 was significantly higher in Qinghai than in other regions. (Domkhar vs. Changthang vs. Qinghai vs. Puyca = 7.0% vs. 5.3% vs. 36.9% vs. 15.5%, P<0.001). However, prevalence of depression by interview did not change in these regions. (1.8% vs. 1.9% vs. 2.3% vs. 2.9%).

Despite the high altitude, the prevalence of depression was low in elderly highlanders in the Himalayas and the Andes. These results may relate to being presumed to related to a deep devotion to a religion and tight interpersonal networks.