老年靜態行為與認知老化之文獻回顧

A Review of Late-life Sedentary Behaviors and Cognitive

身體活動已被視為成功老化的關鍵因子，但靜態生活型態在現今已相當常見。靜態行為被定義為在非睡眠期間任何小於1.5代謝當量的坐或躺之行為，如：看電視、閱讀書報、用電腦/網路、飲食、工作及聊天等。研究指出：過多的靜態時間會提高罹病率及死亡率的風險。因此，這些行為已逐漸被認為是慢性疾病的新危險因子與重要的研究議題。儘管在睡覺以外，老年人花許多時間在靜態行為 (每日約8-12小時)，但有關靜態行為與認知老化間的關係仍然未被完整探討。本研究旨在透過有關老年靜態行為與其認知功能的流行病學研究證據，提供一個敘述性的綜論。為達此目的，本研究首先探討靜態行為對健康的影響? 本文針對成人 (含老年人) 靜態行為與其健康的回顧性研究加以綜整。在14篇研究中，僅1篇是針對老年人進行討論。整體而言，較多的靜態時間與全死因死亡率、心血管疾病、代謝症候群、過重/肥胖、糖尿病、部分癌症與憂鬱症等疾患的風險增加有密切相關。此外，多數研究使用問卷測量靜態行為，只有少數採用客觀儀器 (如：加速規) 測量。然而，有關老年靜態行為與其認知功能的研究，目前尚未獲得足夠關注。其次，本文針對8篇有關老年靜態行為與認知功能的前瞻性研究進行探討。結果發現：總靜態時間也許不是重點，不同種類的靜態行為也許與認知功能有不同的關係。譬如：與看電視相較，用電腦與網路似乎較有助於在老化過程維護認知功能。第三，本文提出靜態行為與認知功能的測量、研究設計、資料分析與潛在作用機轉等議題，並加以評析。最後，提出結論以及在未來研究的建議。綜言之，透過大規模的全國代表性樣本，使用多次測量的前瞻性研究設計，同時兼採主觀問卷與客觀加速規的測量方式，都是值得推薦的。

Although physical activity has been recognized as a key determinant of successful aging, a sedentary lifestyle has been prevalent in modern societies. Sedentary behaviors are defined as any waking behavior characterized by an energy expenditure equal or greater than 1.5 metabolic equivalents (METs) while in a sitting or reclining posture, such as TV watching, reading, computer and internet use, eating, working and social chatting etc. Research evidence showed that too much time in sedentary behaviors could increase the risks of morbidity and mortality. These behaviors have been increasingly regarded as a new risk factor for chronic diseases and a significant health research agenda. Although older adults spend most of their awake time in sedentary activities (ranging in hours per day from approximately 8 o 12), the associations of sedentary behaviors with cognitive aging has not been comprehensively examined. The study aimed to provide a narrative review by scrutinizing the recent epidemiologic evidence for prospective cohort studies of late-life sedentary behaviors and cognitive function in older adults over 65 years old. To fulfill the objective, the following issues were raised and analyzed in an effort to disentangle the complex relationships between late-life sedentary behaviors and cognition. First, what are the effects of sedentary behaviors on various health outcomes? The findings of the recent reviews on this topic in adults (including older adults) were synthesized and compared. Among fourteen reviews, only one was specifically for older adults. Overall, Greater sedentary time was observed to be closely related to increased risks of all-cause mortality, cardiovascular diseases, metabolic syndromes, overweight/obesity, diabetes, some kinds of cancer, and depression. Additionally, most studies tend to adopt questionnaires to assess sedentary behaviors. In contrast, few studies utilized objective instruments, such as accelerometers, to measure sedentary behaviors. To date, less attention, however, has been paid to assess the relation of sedentary behaviors with cognitive function among older adults. Second, the review of prospective cohort studies investigating the relationships between diverse sedentary behaviors and various cognitive outcomes among older adults was conducted. Based on the evidence of eight prospective cohort studies, it revealed that it may be not the total time spent in sedentary behavior that is important. Instead, specific sedentary behaviors are related to cognitive performance among older adults in different ways. For example, in contrast to TV viewing, computer and internet use may be beneficial for maintaining cognitive performance during the aging process. It is possible that computer use is more likely to have the potential to stimulate individuals’ cognitive functioning in an active way rather than a passive way. Third, the research issues regarding measurements of sedentary behaviors and cognitive function, research design, statistical data analysis and potential mechanisms to explain the relations of sedentary behaviors with cognition aging were identified and discussed. Finally, conclusions and suggestions for future research on this topic were proposed. Based on a nationally representative sample, a large-scale prospective cohort study with multiple waves of data collection employs a combination of subjective and objective measures of sedentary behaviors, such as a questionnaire and accelerometry, is recommended.