A meta-analysis of prospective studies on the role of physical activity and the prevention of Alzheimer's disease in older adults.

BACKGROUND: The incidence of Alzheimer's disease is increasing as the global population ages. Given the limited success of pharmaceuticals in preventing this disease, a greater emphasis on non-pharmaceutical approaches is needed. The aim of this study was to quantify the association between Alzheimer's disease and physical activity in older adults over the age of 65 years. METHODS: A meta-analytic approach was used to determine if physical activity reduced the risk of Alzheimer's disease in individuals 65 years or older. Some evidence indicates that physical activity may improve cognitive function in older adults, while other evidence is inconclusive. The purpose of this study was to examine if prevention of Alzheimer's disease is possible if started at a later age. The precise brain changes that occur with the onset of Alzheimer's disease are not fully known, and therefore may still be influenced by preventative measures even in advancing age. Determining if physical activity can inhibit the onset of the disease at any age may motivate individuals to adopt an "it's never too late" mentality on preventing the onset of this debilitating disease. Longitudinal studies of participants who were 65 years or older at baseline were included. A total of 20,326 participants from nine studies were included in this analysis. RESULTS: The fixed effects risk ratio is estimated as 0.61 (95% CI 0.52-0.73) corresponding to a statistically significant overall reduction in risk of Alzheimer's disease in physically active older adults compared to their non-active counterparts. CONCLUSION: Physical activity was associated with a reduced risk of Alzheimer's disease in adults over the age of 65 years. Given the limited treatment options, greater emphasis should be paid to primary prevention through physical activity amongst individuals at high-risk of Alzheimer's disease, such as those with strong genetic and family history.

Overweight and obesity mortality trends in Canada, 1985-2000.

OBJECTIVES: To investigate the temporal trends in the mortality burden attributed to overweight and obesity in Canada between 1985 and 2000. DESIGN: Overweight and obesity prevalence data from six cross-sectional national population surveys, including the 1985 and 1990 Health Promotion Surveys, 1994, 1996 and 1998 National Population Health Surveys, and 2000 Canadian Community Health Survey, in conjunction with one published prospective cohort study on overweight, obesity and mortality. PARTICIPANTS: Adults 20-64 years of age. MAIN OUTCOME MEASURE: The number of deaths attributable to overweight and obesity at the national and provincial levels. Attributable deaths were estimated using the Population Attributable Risk (PAR), which combined the prevalence data with the relative risks of mortality associated with overweight and obesity. A two-way sensitivity analysis was conducted by simultaneously varying the population prevalences and relative risk estimates by +/-10%. RESULTS: Between 1985 and 2000, the national PAR for overweight and obesity increased from 5.1% to 9.3%, and the annual number of deaths attributable to overweight and obesity increased from 2,514 (966-4,061) to 4,321 (2,114-6,542). Cumulatively, 57,181 (25,075-89,227) deaths were attributed to overweight and obesity between 1985 and 2000. Although overweight- and obesity-related mortality is increasing in every province, the problem is particularly pronounced in Eastern Canada. CONCLUSIONS: Overweight and obesity are important public health problems in Canada, accounting for approximately 57,000 deaths over the last 15 years. Immediate and sweeping public health campaigns and interventions are required to slow or reverse the recent trends.

National Cholesterol Education Program Adult Treatment Panel III guidelines and obesity: implications for Canada.

BACKGROUND: The National Cholesterol Education Program Adult Treatment Panel (ATP) III recommendations incorporate new evidence for treating elevated low-density lipoprotein cholesterol. OBJECTIVES: Comparisons between the prevalence of drug-eligible Canadians under the old ATP II and the new ATP III guidelines were made, and the impact of obesity on current and future drug eligibility was explored using various models. METHODS: Participants from the Canadian Heart Health Surveys (1986 to 1992; n=17,728; 20 to 74 years of age) were assigned to therapeutic lifestyle change or drug-eligible groups in the event of elevated low-density lipoprotein cholesterol. Body mass index was used to classify participants as having normal weight, or as being overweight or obese. The prevalence of overweight and obese status for 2001, 2006 and 2011 were projected from past trends by linear regression. Population attributable risk was used to model reductions or increases in the prevalence of obesity in drug-eligible participants using several nationally representative population health surveys. RESULTS: In 2001, an additional 1.1 million Canadians were drug-eligible under ATP III (16.0% of men, 9.5% of women), compared with ATP II (7.7% of men, 7.7% of women). Drug eligibility was elevated in overweight participants (men: OR=1.87 [1.51 to 2.31]; women: OR=1.60 [1.13 to 2.28]) and the obese (men: OR=2.86 [1.86 to 4.38]; women: OR=2.28 [1.63 to 3.18]) versus normal weight participants. The population attributable risk was higher in men (overweight 22.6%, obese 11.5%) than in women (overweight 9.4%, obese 9.2%). IMPLICATIONS: A 10% reduction in overweight and obesity prevalence could have prevented 69,530 cases of drug eligibility in 2001. On the other hand, by 2011 over one million Canadians will be drug-eligible because of an elevated body mass index, if the recent trends in overweight and obese status continue.

Discrimination of health risk by combined body mass index and waist circumference.

OBJECTIVE: NIH Clinical Guidelines (1998) recommend the measurement of waist circumference (WC, centimeters) within body mass index (BMI, kilograms per square meter) categories as a screening tool for increased health risk. RESEARCH METHODS AND PROCEDURES: The Canada Heart Health Surveys (1986 through 1992) were used to describe the prevalence of the metabolic syndrome in Canada and to test the use of the NIH guidelines for predicting metabolic risk factors. The sample included 7981 participants ages 20 to 74 years who had complete data for WC, BMI, high-density lipoprotein-cholesterol, triglycerides, diabetic status, and systolic and diastolic blood pressures. National Cholesterol Education Program Adult Treatment Panel III risk categories were used to identify the metabolic syndrome and associated risk factors. Logistic regression was used to test the hypothesis that WC improves the prediction of the metabolic syndrome, within overweight (25 to 29.9 kg/m(2)) and obese I (30 to 34.9 kg/m(2)) BMI categories. RESULTS: The prevalence of the metabolic syndrome was 17.0% in men and 13.2% in women. The odds ratios (OR) for the prediction of the metabolic syndrome were elevated in overweight [OR, 1.85; 95% confidence interval (95%CI), 1.02 to 3.35] and obese (OR, 2.35; 95%CI, 1.25 to 4.42) women with a high WC compared with overweight and obese women with a low WC, respectively. On the other hand, WC was not predictive of the metabolic syndrome or component risk factors in men, within BMI categories. DISCUSSION: In women already at increased health risk because of an elevated BMI, the additional measurement of WC may help identify cardiovascular risk.