探討臺灣社區老人平均紅血球體積與認知功能之關聯

Abstract

研究背景及目標：平均紅血球體積是在血液常規檢查中常見的檢測項目，可以幫忙輔助貧血的診斷。平均較大的紅血球體積可能比較難以通過微血管、供應組織氧氣和營養素的能力較差，進而影響認知功能。高齡人口的認知功能障礙是近年重要的議題，過去僅有少數研究探討老年族群平均紅血球體積和認知功能障礙之間的關聯性，而且不同的研究間尚無一致的結果，因此本研究主要探討臺灣社區長者平均紅血球體積與認知功能隨時間變化之關聯。 研究方法：本研究是一項為期12年的前瞻性世代研究(2011-2022)，自基線(2011-2013年)時納入530位年齡65歲以上之社區長者，每兩年追蹤一次，共追蹤四次，收集包含平均紅血球體積、血紅素、血小板、紅血球分佈寬度變異係數等血液常規檢查項目，每位受試者另收集血樣分析葉酸、維生素B12的濃度。使用蒙特利爾認知評估臺灣版評估長者的整體認知功能，另外也對記憶、注意力、語言流暢度及執行功能等四項認知功能領域進行評估。研究中使用廣義加成模型圖形的轉折點將平均紅血球體積分組，運用廣義線性混合模型分析長者平均紅血球體積與認知功能隨時間變化，並調整其他重要的因子(例如：年齡、性別、教育程度、血小板、紅血球體積分佈寬度變異係數、葉酸、維生素B12、載脂蛋白E ε4對偶基因帶原等)。 研究結果：受試者的平均年齡為72.7歲，其中女性占53.4%。隨著追蹤時間增加，基線時較大的平均紅血球體積 (平均紅血球體積>93.0 fL)與較差的邏輯記憶-立即回憶（β= -0.028，95% CI = -0.052至-0.004，p值0.021）、邏輯記憶-延遲回憶（β= -0.039，95% CI = -0.063至-0.014，p值0.002）邏輯記憶-延遲主題（β= -0.041，95% CI = -0.068至-0.013，p值0.003）、及注意力-順向記憶廣度評估（β= -0.028，95% CI = -0.052至-0.003，p值0.027）有關。我們同時發現平均紅血球體積與血小板之間在整體認知功能存在交互作用(pinteraction = 0.04)。 結論：平均紅血球體積隨者時間變化對多項認知功能領域會有負向的影響。平均紅血球體積可能可以成為評估認知障礙的早期指標，但是仍須更大型、更長期的研究以了解其中的時間關聯性與潛在機轉。

Background The mean corpuscular volume (MCV) is a common parameter in routine blood tests. Larger MCV tends to be more fragile and pose challenges in passing through capillaries, leading to a diminished capacity for oxygen and nutrient supply to the brain thus impacting cognitive function. Limited studies have explored the association between MCV and cognitive impairment with inconsistent results. This study aimed to investigate the association between MCV and cognitive function in community-dwelling older adults.

Method This 12-year cohort study (2011-2022) included 530 non-demented older adults (aged above 65) from the ongoing Taiwan Initiative for Geriatric Epidemiological Research at baseline (2011 to 2013) with four biennial follow-ups. Global cognition was assessed by the Taiwanese version of the Montreal Cognitive Assessment. Domain-specific cognition, including memory, attention, verbal fluency, and executive function, was assessed by a battery of neuropsychiatric tests. Blood data were collected, including MCV, red blood cell distribution width, hemoglobin, platelet, and vitamin B12. The cutoff of MCV was determined by the turning point obtained from the generalized additive model. This study utilized a generalized linear mixed model to analyze the association between MCV and cognitive function adjusted for age, sex, years of education, apolipoprotein E ε4 status, years of follow-up, and other blood parameters.

Result The average age of the participants is 72.7 years, with females comprising 53.40%. As the follow-up time increased, older adults with larger baseline MCV (>93.0 fL) exhibited a significantly poor performance of memory (immediate free recall: β= -0.028, p = 0.021; delayed free recall: β= -0.039, p = 0.002; delayed theme recall: β= -0.041, p = 0.003), and attention (digit span forward: β= -0.028, p = 0.027). Additionally, interactions were found between MCV and platelet on global cognition (pinteraction = 0.04).

Conclusion Over time, increased MCV was associated with poor domain-specific cognition. MCV may potentially serve as an early indicator for assessing cognitive impairment. Larger and longer-term studies are needed to clarify their temporal relationship and underlying mechanism.