Geriatrics & Gerontological Nursing

The aim is to examine prediction of body mass index (BMI) measured at older age to dementia risk, through a systematic review and a new study. We searched PubMed and 4 other electronic databases till July 2016 and identified 11 cohort studies for review. Four were from USA, two from Finland, two from Sweden, and one each from Denmark, Italy and Australia. Two studies showed a significant prediction of BMI to dementia development, while 9 studies showed a reverse association of BMI with dementia, of which 7 were statistically significant. We examined a random sample of 2755 participants aged ≥60 years in China, who were without dementia and had BMI (kg/m2) measured at baseline. Over a 10-year follow up until 2011, there were 320 dementia occurred. After adjustment for age, sex, education level, urban-rural areas, marital status, life styles, cardiovascular diseases and diabetes, odds ratio for dementia was 0.89 (95%CI 0.66-1.21) in participants with BMI of 23-<26, 0.94 (0.67-1.32) in BMI ≥26, and 0.93 (0.64-1.37) in BMI <22 compared to BMI of 20-<23. In pooling all data available according to different categorized BMI analysis, a relative risk (RR) of dementia was 0.78 (0.64-0.96) in obese people, 0.79 (0.71-0.88) in overweight and 0.95 (0.79-1.14) in underweight in comparison with normal weight, while the pooled RR from those taking continuous BMI analysis was 0.96 (0.93-0.995). The pooled-RR for other different categorised BMI analysis demonstrated similar prediction trends. We conclude that preserving a certain body weight in older age may prevent from

dementia.