Adiposity parameters and cognitive function in the elderly: application of "Jolly Fat" hypothesis to cognition.

Obesity has a strong association with cardiovascular and metabolic diseases, which have also been linked with dementia. While recent studies have reported an association between mid-life obesity and dementia, the role that later-life obesity may have is less clear. A total of 721 community-dwelling elderly (60-85 years old) were selected. Obesity parameters, like body mass index (BMI), waist-hip ratio (WHR), waist circumference (WC), and percent body fat (PBF), as well as cognitive functions were measured over a period of approximately 2 years, and then the relationships between these variables were assessed. The change in cognitive function in the elderly was associated with the baseline assessment of BMI (linearly, beta=0.092), WC (quadratic, beta=1.333), and PBF (linearly, beta=0.097). Using multiple regression analyses, the differences exist in the change of cognitive function over time according to the sex. For men, increased obesity over time when obese in the baseline assessment (BMI, WHR, WC) were associated with a positive change in cognitive function. For women, a decreased obesity over time when obese in the baseline assessment (WHR) and an increased obesity over time when they had a normal adiposity in the baseline assessment (WC) were both associated with cognitive decline. The relationship between obesity and cognitive decline in the elderly is complex and some differences exist between the sexes. The application of the "Jolly Fat" hypothesis to cognitive function can only be applied to elderly men and not to elderly women.