ヒマラヤ地域住民の生活習慣、心血管系機能、認知障害と高所への適応

Abstract

高所では, 低圧と低酸素の他に, 温度, 風, 日照, 紫外線の影響, 昼夜の温度差, 生活様式, その他不明の要因が, 複雑に交錯して, 生命予後・疾病予後に影響を及ぼし, 高所地域住民の寿命は60歳余りと短いとされている. そこで本研究では, 平地に住む高知県T 町ならびに北海道U 町の地域住民の調査結果と比較することにより, ヒマラヤ地域に住む高所住民の健康のあり方を考察した. 2004年8月-2008年7月の間に, ラダック(Ladakh)地域の41集落(標高3300m から4590m)地域住民946名(13-92 歳, 平均51.4 歳, 男453 名, 女493 名)を対象に, 総合的機能評価を行ない, 北海道U 町住民183名と, 高知県T 町住民311名の, フィールド医学調査と比較した. 冠動脈疾患とメタボリック症候群の頻度は, 各々, 2%, 3%と少なく, 心房細動例は認められなかった. 一方, 頭痛の訴えは32%と多かった, ラダック地域住民の睡眠時間は, U町住民よりも長かったが(p < 0.01), 就眠までの時間は, 短時間であった(25.6 vs. 15.5 分, p < 0.005). ラダック住民は, 歩く速さが遅く(Up & Go; 12.9 vs. 14.6sec, p < 0.0005), Functional Reach が短く(26.4 vs. 21.7cm, p < 0.05), ボタンつけはずしに長い時間を要した(p < 0.00001). SpO2 はT 町に比し低く(96.6 vs. 85.2%, p < 0.00001), 呼吸数は頻数であった(18.3 vs. 22.1回/分, p <0.00005). Kohs 立方体試験の得点が, T町住民より51.7%も低値であり(11.3 vs. 23.4 スコア, p < 0.00001), 10 秒の時間予測が短く(p < 0.00001), 認知機能の低下が推察された. 臥位の拡張期血圧が, ラダック住民で高く(79.0 vs. 71.0mmHg, p < 0.000), 脈拍数は高値であった(74.0 vs. 65.8bpm, p < 0.001)が, 血管の硬さには, 差を認めなかった. ラダック地域の高所住民は, 苛酷な低酸素環境にもかかわらず, 特有な生活習慣を身につけ, 順応し, 適応している. 高所地域住民の生命予後・疾病予後を改善するには, 医学的検査とともに, 生活習慣や環境要因, ADL 機能や認知機能などを, 総合的に評価し, 地域に即した診断と治療を求めるという医療のとり組み(Glocal Comprehensive Assessment, GCA)が必要である.

This investigation was particularly focused on chronoecology in Ladakh, to study quality of health as a physiological system at high altitude, as a comparison with the chronoecological study in Japanese T-town, Kochi and U-town, Hokkaido. Effects of high altitude on life style and cardiovascular function were studied by glocal (i.e., global and local) comprehensive assessment, including a questionnaire on sleep habit, in 946 Ladakhis (from 13 to 92 years, average 51.4 years of age, 453 men and 493 women), living at altitudes of 3300 to 4590 m, and in Japanese residents of 183 U-town and 311 T-town. Residents in the high-altitude community of Ladakh had a less frequent suffering from coronary artery disease, atrial fibrillation and metabolic syndrome (3%, 0%, 3%, respectively), but a longer sleeping time (p<0.01) and a shorter time for falling asleep (25.6 vs. 15.5 min., p<0.005). Ladakhis walked slow, estimated by Up&Go test (12.9 vs. 14.6 sec､p<0.0005), showed a shorter record of the functional reach test (26.4 vs. 21.7 cm､p<0.05), and took a longer time of the Button test (p<0.00001). SpO2 was lower (84.4 vs. 96.0 %, p<0.00001), and respiration rate was faster (18.3 vs. 22.1 times/min､p<0.00005) compared with U-town residents. Score of the Kohs' block test was lower (11.3 vs. 23.4 score, p<0.00001), and time estimation of 10-sec was statistically significantly shorter (p<0.0001), and diastolic blood pressure and pulse rate were higher than the U-town (79.0 vs. 71.0 mmHg, ; 74.0 vs. 65.8 bpm､p<0.001, respectively). However, there were no statistical difference of brachial-ankle and heart-ankle pulse wave velocities between them. In conclusion, people living at high altitude have a higher risk of cardiovascular disease than the low-altitude peers, although it has been fully habituated and fully adapted, which indicates the need for a global comprehensive assessment for a more fruitful treatment. Longitudinal observations of effects of socio-ecologic factors on the cardiovascular system should help prevent strokes and other cardiovascular events, especially at high-altitude.