Effects of Diabetes and Physical Activity on the Change of Cognitive Functions in Elderly in Taiwan: 8-year longitudinal study

• Main Authors: Yun-WenWang, 王允汶
• Other Authors: Susan C. Hu
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/j24xx9

碩士 === 國立成功大學 === 行為醫學研究所 === 104 === Background: 18%–33% of elderly people have diabetes, and diabetes is related to diabetes-related cognitive impairment. Although studies have revealed that a highly active lifestyle significantly prevented cognitive decline. Limited studies have thoroughly explored whether increasing physical activity can serve as one of the strategies for mitigating diabetes-related cognitive decline. Only three studies have been conducted to investigate the relationship between physical activity and the cognitive function of diabetic patients. To date, researchers have yet to thoroughly explore whether increasing physical activity can serve as one of the strategies for mitigating diabetes-related cognitive decline. Objectives: This study aimed to determine the effects of diabetes and physical activity on the overall cognitive function of elderly people in Taiwan after 8-year follow-up. The objectives of this study were as follows: a) to determine the overall cognitive function impairment in elderly patients with diabetes in Taiwan; b) to determine the current status of elderly patients with diabetes in Taiwan engaging in physical activities; c) to determine the effects of diabetes and physical activity on the cognitive functions of elderly patients with diabetes in Taiwan. Methods: The Taiwan Longitudinal Survey of Aging (TLSA) database was adopted in this study. This study employed a panel study approach, investigating the effects of physical activity and diabetes on cognitive function decline. The survey year of 1999 was adopted as the starting point for observation. The 1999 survey recruited 2709 participants aged 65 years and above; excluding 230 whose ADL scored ≥1, 480 who had difficulty walking 200–300 m, 91 who failed to answer more than one questions on the SPMSQ (unknown or unfit), and 2 whose physical fitness status was unknown, a total of 1906 participants were recruited for the 1999 survey. In the 2007 survey, of the 1906 participants recruited in 1999, 581 had deceased, 3 had immigrated, and 66 provided incomplete questionnaire response, yielding a total valid response of 1256 in 2007. Moreover, excluding the 169 respondents who failed to answer more than one questions on the 9-item SPMSQ (unknown or unfit), the 2007 survey incorporated 1087 participants. The participants recruited for this study were relatively naïve, and the research period comprised 1999–2007 to investigate how regular physical activity and disease type influence cognitive decline. Disease types were measured by asking “Do you have the following disease, which was diagnosticed by physicians?” and then was categorized into 3 groups: Diabetes (DM group), Cardiovascular diseases (CVD group, including heart disease, high blood pressure, and stroke), and No DM and no CVD (NN group). For those who have DM and CVD, it was grouped into DM group. Physical activity (PA) was measured by engaging moderate exercise for at least 150 minutes per week. According to the status of physical activity in 1999 and 2007, all eligible participants were divided into 4 groups: continuing engage in PA and reach the stardand, later engage in PA and reach the standard, later stop engage in PA or not reach the standard, continuing no PA or not reach the standard. The 1997 and 2007 9-point Short Portable Mental-Status Questionnaire (SPMSQ) was used as the basis for cognitive function. The objective was to determine whether the elderly people had intellectual impairment and the level of impairment. Statical methods included descriptive, bivariate, and multiple regression. Results: Of the 1906 participants in baseline year, 12.4% of the surveyed elderly people had diabetes, 34.3% had cardiovascular disease, and 53.1% had no diabetes and no cardiovascular disease. The SPMSQ results revealed that approximately 90% of the elderly people had normal cognitive function, whereas 5.1% of them may have cognitive impairment. Although the diabetes group achieved lower SPMSQ scores compared with the cardiovascular disease group and the reference group, these scores were statistically nonsignificant. A greater number of participants in the NN group did not exercise compared with those in the diabetes and cardiovascular disease groups, whereas a greater number of participants in the diabetes group had significantly achieved exercise goal (p=.029) compared with the other two groups. Regarding the long-term conditions of the cognitive impairment among patients with diabetes, the 1999–2007 SPMSQ scores differed significantly (p=.001–.013) according to age and education level. The difference in the 1999–2007 SPMSQ scores reduced by .35 (p=.067) among patients who continued to have diabetes compared with those without diabetes or cardiovascular disease. The difference in the 1999–2007 SPMSQ scores increased by .53 (p=.000) among patients who started exercising afterward and achieved exercise goal compared with those who did not continue to exercise or did not achieve exercise goal. Finally, the results were analyzed using a regression analysis model, which comprised the following variables: sociademographic variables, disease type, regular exercise, smoking, alcohol intake, total depression score, total number of leisure activityies and community groups. This model was employed to predict the cognitive differences among the samples collected from the 1999–2007 survey results. The prediction results achieved statistical significance (F=4.725, R2=.088). The difference in the 1999–2007 SPMSQ scores increased by .26 among patients who continued to achieve exercise goal compared with those who did not continue to exercise or achieve exercise goal. The difference in the 1999–2007 SPMSQ scores increased by .53 (p=.000) among patients who started exercising afterward and achieved exercise goal compared with those who did not continue to exercise or did not achieve exercise goal. The difference in the 1999–2007 SPMSQ scores reduced by .24 among patients who stopped exercising afterward and those who failed to achieve exercise goal compared with those who did not continue to exercise or did not achieve exercise goal. Regarding disease category, the difference in the 1999–2007 SPMSQ scores reduced by .35 (p=.067) among patients who continued to have diabetes compared with those in the NN group; the difference in the 1999–2007 SPMSQ scores reduced by .26 among patients whose condition developed into diabetes compared with those in the NN group; the difference in the 1999–2007 SPMSQ scores increased by .05 among patients who continued to have cardiovascular disease compared with those in the NN group; and the difference in the 1999–2007 SPMSQ scores reduced by .12 among patients whose condition developed into cardiovascular disease compared with those in the NN group. Discussion: The findings of this study revealed that elderly people with diabetes can delay their cognitive decline by engaging in physical activity, thereby achieve the goal of active aging. Because the underlying pathology of diabetes and cognitive decline may initiate many years prior to the onset of the clinical disease, long-term physical activity and regular evaluation of diabetic patients’ cognitive function may be important. The adverse cognitive effects of diabetes are interdisciplinary and diverse; therefore, they may differ among different elderly age groups. Future studies should analyze participants of varying ages and how their physical activity is related to specific cognitive function. In longitudinal studies, sample loss is attributed to the following reasons: (a) mortality, (b) health or other related factors, and participant withdrawal, (c) changes of residential address, region, and type, and (d) failure to respond. Such loss may compromise the sample representativeness. Some people did not participate again because of systematic elements such as poverty, frailty, or physical strength. Future researchers could investigate the underlying mechanisms through which exercising improves diabetes-related cognitive impairment. Previous findings indicated that the potential effect of physical activity on improving cognitive aging and enhancing cognitive performance can be examined by classifying participants according to their habit of engaging in regular exercise in the past 3 to 5 years. This study contributed to relevant research by including 1906 participants and adopting a panel study approach to investigate how regular physical activity and disease category influence cognitive decline. Nevertheless, this study still had several limitations. Firstly, this study did not attempt to understand whether the blood glucose level of diabetic patients was properly controlled and their weekend sitting behavior. Secondly, this study lacked the information on the year in which the participants received their diagnosis (i.e., diabetes). Past studies have estimated that 30% of elderly people had not had their diabetes condition been diagnosed; if these people are included into the control group, the effect of diabetes on risk of dementia may be underestimated.