AIMS: We examined the individual association between body mass index (BMI) and cognitive function among the very elderly. METHODS: The present study analyzed data from a survey that was conducted on all residents aged 90 years or more from a district which had 2,311,709 inhabitants in 2005. The subjects were divided into 4 groups according to quartiles of BMI (<16.6, 16.6-18.9, 18.9-21.1 and >21.1), and according to classification criteria of underweight, normal weight, overweight and obesity in BMI (<18.5, 18.5-23.0, 23.0-27.5 and >27.5), respectively. RESULTS: The subjects included in the statistical analysis were 211 men and 427 women. Those in the 3rd quartile of BMI (18.9-21.1) had higher cognitive function scores (p < 0.001) and were less likely to present possible dementia (p = 0.016) than the others. However, there was no difference in cognitive function scores (p = 0.350) or prevalence of possible dementia (p = 0.263) among obesity, overweight, normal weight and underweight groups. CONCLUSIONS: Concerning longevity in Chinese, there is an association between BMI and cognitive function. BMI of around 20 (18.9-21.1) is associated with the lowest risk of prevalence of possible dementia and the highest cognitive function scores.
AIMS: We examined the individual association between body mass index (BMI) and cognitive function among the very elderly. METHODS: The present study analyzed data from a survey that was conducted on all residents aged 90 years or more from a district which had 2,311,709 inhabitants in 2005. The subjects were divided into 4 groups according to quartiles of BMI (<16.6, 16.6-18.9, 18.9-21.1 and >21.1), and according to classification criteria of underweight, normal weight, overweight and obesity in BMI (<18.5, 18.5-23.0, 23.0-27.5 and >27.5), respectively. RESULTS: The subjects included in the statistical analysis were 211 men and 427 women. Those in the 3rd quartile of BMI (18.9-21.1) had higher cognitive function scores (p < 0.001) and were less likely to present possible dementia (p = 0.016) than the others. However, there was no difference in cognitive function scores (p = 0.350) or prevalence of possible dementia (p = 0.263) among obesity, overweight, normal weight and underweight groups. CONCLUSIONS: Concerning longevity in Chinese, there is an association between BMI and cognitive function. BMI of around 20 (18.9-21.1) is associated with the lowest risk of prevalence of possible dementia and the highest cognitive function scores.