Higher Prevalence of Cognitive Impairment in Residents of High-Altitude Regions

Abstract

Introduction: A major health issue in individuals living at high-altitude regions is an increase in the number of red blood cells (RBCs). This condition generates a series of physiological alterations including the nervous system, where damage can occur due to increased blood viscosity. This increased viscosity, in turn, could compromise oxygen uptake, potentially linked to a degree of cognitive impairment. Objective: To determine the association between exposure to chronic hypoxia and sleep quality with the degree of cognitive impairment in a young adult population residing at different altitude levels. Methodology: A cross-sectional study was conducted with 200 apparently healthy subjects (aged 21–26 years) permanently residing in four Peruvian cities: Lima (154 m), Arequipa (2,335 m), Puno (3,820 m), and La Rinconada (5,100 m) (n= 50 per location). Physiological profiles (SpO , blood pressure, heart rate, hemoglobin, and hematocrit) were measured. Cognitive impairment and sleep quality were evaluated using the Montreal Cognitive Assessment (MoCA) and the Pittsburgh Sleep Quality Index (PSQI). Sex-stratified hierarchical multiple linear regression models with bootstrapping were utilized for independent correlation analysis. Results: Hemoglobin levels gradually increased with altitude, peaking at 19.47 ± 3.01 g/dL in La Rinconada, while SpO2 decreased to 81.64%. Moderate-to-severe cognitive impairment was exclusively restricted to the extreme altitude population of La Rinconada, where only 10% of subjects remained unaffected. In the sex-stratified multivariate regression, residency in La Rinconada initially served as a robust negative predictor of MoCA scores among women (β = −5.52, p < 0.001); however, this geographical effect lost statistical significance after adjusting for biological variables in Model 2 (β = −4.72, p = 0.178). In the fully adjusted models, neither individual hemoglobin levels nor SpO2 fluctuations displayed an independent linear association with cognitive performance in either sex (p > 0.05). Sleep quality was poor across cohorts but showed no significant association with cognitive impairment (p = 0.174). Conclusions: Chronic exposure to severe hypoxia (>5000 m) is associated with a greater presence of cognitive impairment, which is largely accounted for by individual physiological adaptations rather than isolated, linear effects of independent hematological or subjective sleep parameters [M1]Please confirm if the bold formatting is necessary; if not, please remove it. The following highlights are the same. [M2]Please confirm whether “n” is a variable and should therefore appear in italics. If yes, please revise in the whole text. [M3]Please check if 2 should be subscript. If yes, please revise in the whole text.