title: Domain specific changes in cognition at high altitude and its correlation with hyperhomocysteinemia.
abstract: Though acute exposure to hypobaric hypoxia is reported to impair cognitive performance, the effects of prolonged exposure on different cognitive domains have been less studied. The present study aimed at investigating the time dependent changes in cognitive performance on prolonged stay at high altitude and its correlation with electroencephalogram (EEG) and plasma homocysteine. The study was conducted on 761 male volunteers of 25-35 years age who had never been to high altitude and baseline data pertaining to domain specific cognitive performance, EEG and homocysteine was acquired at altitude ≤240 m mean sea level (MSL). The volunteers were inducted to an altitude of 4200-4600 m MSL and longitudinal follow-ups were conducted at durations of 03, 12 and 18 months. Neuropsychological assessment was performed for mild cognitive impairment (MCI), attention, information processing rate, visuo-spatial cognition and executive functioning. Total homocysteine (tHcy), vitamin B12 and folic acid were estimated. Mini Mental State Examination (MMSE) showed temporal increase in the percentage prevalence of MCI from 8.17% on 03 months of stay at high altitude to 18.54% on 18 months of stay. Impairment in visuo-spatial executive, attention, delayed recall and procedural memory related cognitive domains were detected following prolonged stay in high altitude. Increase in alpha wave amplitude in the T3, T4 and C3 regions was observed during the follow-ups which was inversely correlated (r = -0.68) to MMSE scores. The tHcy increased proportionately with duration of stay at high altitude and was correlated with MCI. No change in vitamin B12 and folic acid was observed. Our findings suggest that cognitive impairment is progressively associated with duration of stay at high altitude and is correlated with elevated tHcy in the plasma. Moreover, progressive MCI at high altitude occurs despite acclimatization and is independent of vitamin B12 and folic acid.
authors.affiliation: Defence Institute of High altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh, India.
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Sharma
authors.affiliation: Defence Institute of High altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh, India.
authors.forename: Saroj K
authors.initials: SK
authors.lastname: Das
authors.affiliation: Defence Institute of High altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh, India.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Dhar
authors.affiliation: Defence Institute of High altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh, India.
authors.forename: Kalpana B
authors.initials: KB
authors.lastname: Hota
authors.affiliation: Department of Statistics, Population Council, New Delhi, India.
authors.forename: Bidhu B
authors.initials: BB
authors.lastname: Mahapatra
authors.affiliation: Defence Institute of High altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh, India.
authors.forename: Vivek
authors.initials: V
authors.lastname: Vashishtha
authors.affiliation: Defence Institute of High altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh, India.
authors.forename: Ashish
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Defence Institute of High altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh, India.
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Hota
authors.affiliation: Ladakh Institute of Prevention, Dambuchan, Leh-Ladakh, India.
authors.forename: Tsering
authors.initials: T
authors.lastname: Norboo
authors.affiliation: Defence Institute of High altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh, India.
authors.forename: Ravi B
authors.initials: RB
authors.lastname: Srivastava
mesh_terms: D000064:Acclimatization; D000328:Adult; D000531:Altitude; D003071:Cognition; D060825:Cognitive Dysfunction / Q000097:blood / Q000209:etiology*; D005492:Folic Acid / Q000097:blood; D005500:Follow-Up Studies; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000097:blood / Q000209:etiology*; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D014805:Vitamin B 12