Assessing the effect of long-term high altitude exposure on human brain function: A resting-state functional magnetic resonance imaging study

OBJECTIVE: This study uses resting-state functional magnetic resonance imaging (fMRI) to understand and compare the effects of hypoxic conditions at high and ultra-high altitudes. METHODS: Regional homogeneity (ReHo) and degree centrality (DC) values were calculated and compared between 47 low-altitude (LA, <500m), 39 high-altitude (HA, 1520m), and 34 ultra-high-altitude (UHA, 3650m) healthy adults. Correlations with heart rate and blood oxygen saturation (SpO₂) were analyzed. RESULTS: Compared to the LA group, the UHA/HA group had significantly lower ReHo values in the bilateral basal ganglia, prefrontal lobes (left/right), left paracentral lobule, and these were positively correlated with SpO₂. Conversely, ReHo values were significantly higher in the bilateral posterior occipital and left superior parietal lobes, and were negatively correlated with SpO₂. DC values were significantly lower in the left orbitofrontal cortex, bilateral pallidum and left inferior frontal gyrus, and were positively correlated with SpO₂. Synchronous decreases in ReHo and DC were found in the left prefrontal cortex, bilateral pallidum and putamen. CONCLUSION: In high-altitude environments, functional activity is decreased in the basal ganglia, prefrontal cortex, and hippocampus, is accompanied by a compensatory increase in the occipital and superior parietal lobes. Concurrent reductions in DC and ReHo within the left prefrontal cortex, bilateral pallidum and putamen might serve as biomarkers for high-altitude hypoxic functional alterations and aid early detection and intervention of hypoxia-induced brain damage.