Neurophysiological evidence for cognitive and brain functional adaptation in adolescents living at high altitude Cassandra Richardson a,b,⇑ , Alexandra M. Hogan c , Romola S. Bucks b , Ana Baya d , Javier Virues-Ortega e,f , John W. Holloway h , Matthew Rose-Zerilli h , Lyle J. Palmer i,j , Rebecca J. Webster i , Fenella J. Kirkham g , Torsten Baldeweg c a School of Psychology, University of Southampton, UK b Neurocognitive Development Unit, School of Psychology, University of Western Australia, Western Australia, Australia c Developmental Cognitive Neuroscience Unit, UCL Institute of Child Health, University College London (UCL), UK d Universidad del Valle, Cochabamba, Bolivia e Psychology Department, University of Manitoba, Canada f Saint Amant Research Centre, Winnipeg, Canada g Neurosciences Unit, UCL Institute of Child Health, University College London (UCL), UK h School of Medicine, University of Southampton, UK i Centre for Genetic Epidemiology and Biostatistics, University of Western Australia, Perth, Western Australia, Australia j Ontario Institute for Cancer Research, Toronto, Canada article info Article history: Accepted 3 February 2011 Available online 4 March 2011 Keywords: Altitude EEG ERP Adolescence Cognition highlights  Unique naturalistic study of high altitude on brain functions in adolescents.  We used electroencephalography (EEG) and event-related potentials (ERPs).  Cerebral blood flow was measured by transcranial Doppler sonography (TCD).  There was no indication of negative sequelae of chronic hypoxia.  Dynamic regulation of metabolic demand preserves cognitive development at altitude. abstract Objective: Neurophysiological methods were used to study the effects of high altitude living on brain functions in a subgroup of participants of the Bolivian Children Living at Altitude (BoCLA) project. Methods: Electroencephalogram (EEG), event-related potentials (ERP) and cerebral blood flow velocity (CBFV) were recorded in two groups of adolescents (aged 13–16 years), living either at sea-level or high altitude (3700 m). Results: Neuropsychological testing revealed no deficits in the high altitude group, despite significantly reduced blood oxygen saturation. In agreement, ERPs elicited by oddball target detection and choice reac- tion time tasks were not different between groups. In contrast, resting state EEG showed reductions in delta and beta frequency amplitudes in adolescents living at high altitude. The EEG attenuations were correlated with lower CBFV, and the EEG group differences diminished during task performance. Conclusions: No indication was found for negative sequelae of chronic hypoxia in adolescents born and living at an altitude of 3700 m, rather evidence for successful neurophysiological adaptation was found under such conditions. Significance: Dynamic regulation of metabolic demand is one adaptive mechanism that preserves cogni- tive development at high altitude. Ó 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved. 1. Introduction A chronic reduction in oxygen supply to the brain, hypoxaemia, is associated with reduced cognitive function in children living at sea-level, irrespective of presence of brain infarcts (Hogan et al., 2006). However, millions of children currently live at altitudes in excess of 2500 m (Penaloza and Arias-Stella, 2007), where oxygen 1388-2457/$36.00 Ó 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.clinph.2011.02.001 ⇑ Corresponding author at: Centre for Psychological Research, University of Derby, Faculty of Education, Health and Sciences, Kedleston Road, Derby DE22 1GB, UK. Tel.: +44 1332 591480; fax: +44 1332 597747. E-mail address: c.richardson@derby.ac.uk (C. Richardson). Clinical Neurophysiology 122 (2011) 1726–1734 Contents lists available at ScienceDirect Clinical Neurophysiology journal homepage: www.elsevier.com/locate/clinph