Development of aptitude at altitude

Abstract

Millions of people currently live at altitudes in excess of 2500 metres, where oxygen supply is limited, but very little is known about the development of brain and behavioural function under such hypoxic conditions. We describe the physiological, cognitive and behavioural profile of a large cohort of infants (6-12 months), children (6-10 years) and adolescents (13-16 years) who were born and are living at three altitude locations in Bolivia ( approximately 500 m, approximately 2500 m and approximately 3700 m). Level of haemoglobin oxygen saturation and end-tidal carbon dioxide were significantly lower in all age groups living above 2500 metres, confirming the presence of hypoxia and hypocapnia, but without any detectable detriment to health. Infant measures of neurodevelopment and behaviour yielded comparable results across altitude groups. Neuropsychological assessment in children and adolescent groups indicated a minor reduction in psychomotor speed with increasing altitude, with no effect of age. This may result from slowing of underlying brain activity in parallel with reduced cerebral metabolism and blood flow, evidenced here by reduced cerebral blood flow velocity, particularly in the basilar artery, in children and adolescents. The proportion of European, Native American and African genetic admixture was comparable across altitude groups, suggesting that adaptation to high altitude in these children occurred in response to chronic hypoxic exposure irrespective of ethnic origin. Thus, psychomotor slowing is proposed to be an adaptive rather than a deficient trait, perhaps enabling accuracy of mental activity in hypoxic conditions.

Structural Modifications of the Brain in Acclimatization to High-Altitude

“…A recently study of Hogan et al [68] may support our hypothesis. Hogan et al([68] tested a reduced psychomotor speed in children (6–10 years) and adolescents (13–16 years) of mixed-ethnic background (including Native American, European or African ancestry whose ancestor immigrate to HA during different periods) who were born and raised at HA, they found the reduced psychomotor speed was well correlated with the reduced cerebral metabolism and blood flow. For the proportion of European, Native American and African genetic admixture was comparable across altitude groups, therefore, chronic hypoxic exposure rather than genetic inheritance appears to affect the neurocognitive development at HA.…”

Cortical Thickness of Native Tibetans in the Qinghai-Tibetan Plateau

“…45 For the proportion of Native Americans, Europeans, and Africans, genetic admixture with reduced psychomotor speed was comparable across altitude groups; therefore, chronic hypoxic exposure rather than genetic inheritance appears to affect brain function development at HA. However, pulmonary function (forced expiratory volume and forced vital capacity) measures were greater in the HA natives compared with the lowland natives born and raised at HAs; this finding suggests a genetic effect.…”

Domiciliary Oxygen: Facts and fallacies

“…These results indicate that permanent residents are not maximally adapted since their physical capacity improves to low altitude oxygenation levels. Neuropsychological functions are also altered in high-altitude residents compared with low-level resident controls, and cognitive development of children is decreased at high altitudes, although additional studies are required [70][71][72][73][74]. The results suggest that permanent residents at great heights can improve their neuropsychological function by descending to low altitudes.…”