| 英文摘要 |
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. |
