title: 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.
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Hogan
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: Javier
authors.initials: J
authors.lastname: Virues-Ortega
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: Ana Baya
authors.initials: AB
authors.lastname: Botti
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: Romola
authors.initials: R
authors.lastname: Bucks
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: John W
authors.initials: JW
authors.lastname: Holloway
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Rose-Zerilli
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: Lyle J
authors.initials: LJ
authors.lastname: Palmer
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Webster
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: Torsten
authors.initials: T
authors.lastname: Baldeweg
authors.affiliation:  UCL Institute of Child Health, London, UK CIBER in Neurodegenerative Diseases (CIBERNED), Madrid, Spain Child Health, Nutrition Unit, Prince Leopold Institute of Tropical Medicine, Belgium School of Psychology, University of Western Australia, Australia Divisions of Human Genetics and Infection, Inflammation & Repair, School of Medicine, University of Southampton, UK Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Australia School of Medicine, University of Southampton, UK.
authors.forename: Fenella J
authors.initials: FJ
authors.lastname: Kirkham
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D000293:Adolescent; D000367:Age Factors; D000531:Altitude; D000704:Analysis of Variance; D000886:Anthropometry; D001783:Blood Flow Velocity; D001838:Bolivia; D002245:Carbon Dioxide / Q000097:blood; D054022:Cerebrum / Q000098:blood supply / Q000000981:diagnostic imaging; D002648:Child; D002657:Child Development; D003430:Cross-Sectional Studies; D006454:Hemoglobins / Q000737:chemistry; D006801:Humans; D007223:Infant; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D011597:Psychomotor Performance / Q000502:physiology*; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D006454:Hemoglobins; D002245:Carbon Dioxide; D010100:Oxygen