Gender and Age Differences in Corpus Callosum Morphology: High-Altitude Adaptations in Native Tibetan Populations.

Abstract

Background and aims: The corpus callosum is recognized as the largest interhemispheric white matter structure, coordinating distinct functions of the brain. High-altitude environments may influence the structure of the corpus callosum. This study aims to evaluate the morphologic characteristics of the corpus callosum in Tibetans residing on the Qinghai-Tibet Plateau while investigating the effects of sex, age, and high-altitude exposure on its morphology.

Materials and methods: The study comprised 262 healthy native Tibetan adults, including 113 men and 149 women. The length, height, area, and thickness of each subregion of the corpus callosum were measured, with the data normalized according to brain length and mid-sagittal cortical brain area. Statistical analyses were conducted utilizing nonparametric tests and partial correlation analysis.

Results: Most normalized morphologic measurements indicated significant sex differences, particularly in the thickness of the rostrum (z=-3.199, P=0.001), genu (z=-3.133, P=0.002), body (z=-3.612, P<0.001), splenium (z=-2.279, P=0.02), and callosal length (z=-2.722, P=0.006), and area (z=-2.179, P=0.03). The callosal area (R2=0.084, P<0.001) demonstrated an inverted U-shaped trajectory throughout the lifespan, peaking at ∼40 years of age.

Conclusions: This study identified pronounced sex differences in the corpus callosum morphology among Tibetans. Despite living at high altitudes, the age-related trajectory of the callosal area resembled patterns observed in other populations, although peak ages differed by sex.