臺灣社區老年人體脂肪量或骨骼肌量與認知功能之關聯研究

Abstract

背景：過去研究針對老年人體脂肪量或骨骼肌量和認知功能關聯性的研究結果不一致，且東方人的體型與身體組成和西方人有顯著的差異。臺灣社區老年人依照男性及女性分別探討身體組成改變(例如：體脂肪堆積與骨骼肌量減少)和認知功能相關的研究較少。

研究方法：本篇為橫斷性研究(2015至2017年)，是一進行中之世代追蹤研究(2011至今)的一部分，共446名65歲以上臺灣社區老年人納入本研究分析。依變項為總體認知與認知領域(包含邏輯記憶、執行功能、注意力及語意流暢度)，自變項為生物阻抗分析儀所量測的體脂肪量與骨骼肌量。由於男女在賀爾蒙、體型及生理方面之差異，所有統計分析依性別分層，使用線性回歸模型及羅吉斯回歸模型估計體脂肪量或骨骼肌量與認知功能間的關聯性，並調整重要變數。

結果：在女性長者中發現，高體脂肪量者[最高三分之一(T3)]比起低體脂肪量者(T1)的邏輯記憶障礙的風險較高(迴歸係數β = -0.37，95%信賴區間 = -0.63至 -0.10，Ptrend = 0.01；勝算比= 2.36，95%信賴區間= 1.03至5.44，Ptrend = 0.04 )；以及低骨骼肌量者(T1)比起高骨骼肌量者(T3)的邏輯記憶(迴歸係數β = -0.34，95%信賴區間= -0.60至-0.08，Ptrend = 0.01；勝算比= 2.45，95%信賴區間= 1.07至5.63，Ptrend = 0.04)與執行功能(勝算比= 2.56，95%信賴區間= 1.04至6.30，Ptrend = 0.04) 障礙的風險較高。

結論：女性長者高體脂肪量或低骨骼肌量，顯著增加邏輯記憶與執行功能障礙的風險。男性長者在體脂肪量、骨骼肌量與認知功能在本研究並未有顯著關聯。未來仍需長期縱貫性的資料來呈現身體組成隨著年齡的變化，以及其與認知功能或其他疾病之間的交互影響。

Background: Previous studies exploring the association of body fat mass or skeletal muscle mass with cognitive function has not been consistent. In addition, body composition shows significant differences between eastern and western populations. In Taiwan, only limited studies have explored the change of body composition (e.g., body fat mass accumulation or loss of skeletal muscle mass) in relation to cognitive function by gender in community-dwelling Taiwanese elders.

Method: This is a cross-sectional study (2015-2017) from an ongoing cohort study (2011-present). A total of 446 community-dwelling elderly aged 65 years and older were included for analysis. The dependent variables included global and domain specific (which included logical memory, executive function, verbal fluency and attention) cognitive function. Independent variables were body fat mass and skeletal muscle mass, which were assessed by bioelectrical impedance analysis (BIA). Linear regression and logistic regression models were used to assess the associations between body fat mass or skeletal muscle mass and cognitive function, stratified by gender and adjusting for important covariates.

Results: In old women, the highest tertile (T3) of body fat mass was associated with an increased risk of impaired logical memory compared with the lowest tertile (T1) (β= -0.37, 95% CI= -0.63 to -0.10, Ptrend= 0.01; OR= 2.36, 95% CI= 1.03 to 5.44, Ptrend= 0.04). In addition, the lowest tertile (T1) of skeletal muscle mass significantly increased the risk of impaired logical memory (β= -0.34, 95% CI= -0.60 to -0.08, Ptrend= 0.01; OR= 2.45, 95% CI= 1.07 to 5.63, Ptrend= 0.04) and executive function (OR= 2.56, 95% CI= 1.04 to 6.30, Ptrend= 0.04) compared with the highest tertile (T3) in old women.

Conclusion: Higher body fat mass or lower skeletal muscle mass in old women was significantly associated with an increased risk of impaired logical memory or executive function. In old men, no significant associations were observed between body fat mass or skeletal muscle mass and cognitive function. Further longitudinal research is needed to explore the association between age-related change of body composition and cognitive function or other diseases.