Longitudinal examination of obesity and cognitive function: results from the Baltimore longitudinal study of aging.

BACKGROUND: Obesity indices (i.e. BMI, waist-to-hip ratio) show differential relationships to other health outcomes, though their association to neurocognitive outcome is unclear. METHODS: We examined whether central obesity would be more closely associated with cognitive function in 1,703 participants from the Baltimore Longitudinal Study of Aging. RESULTS: Longitudinal mixed-effects regression models showed multiple obesity indices were associated with poorer performance in a variety of cognitive domains, including global screening measures, memory, and verbal fluency tasks. Obesity was associated with better performance on tests of attention and visuospatial ability. An obesity index by age interaction emerged in multiple domains, including memory and attention/executive function. CONCLUSION: Obesity indices showed similar associations to cognitive function, and further work is needed to clarify the physiological mechanisms that link obesity to poor neurocognitive outcome.

Association of adiposity status and changes in early to mid-adulthood with incidence of Alzheimer's disease.

Adiposity status and change are potential risk factors for Alzheimer's disease (AD). The authors used data on 2,322 participants in the Baltimore Longitudinal Study of Aging to analyze the relation between AD incidence and adiposity in Cox proportional hazards models, with adjustment for sociodemographic factors and smoking status. Body mass index (BMI; weight (kg)/height (m)(2)) and waist circumference at specific ages were predicted by empirical Bayes estimators from mixed-effects regression models. After a median of 23.4 years of follow-up between 1958 and 2006, 187 participants developed AD. Among men, being underweight (BMI or=30) at age 30, 40, or 45 years and jointly centrally obese (waist circumference >or=80th percentile) at age 30, 35, or 50 years increased AD risk (HR = 6.57, 95% CI: 1.96, 22.02). Women who lost weight (BMI change <10th percentile) between ages 30 and 45 years were also at increased risk (HR = 2.02, 95% CI: 1.06, 3.85). Weight gain among men (BMI change >90th percentile) between ages 30 and 50 years increased AD risk (HR = 3.70, 95% CI: 1.43, 9.56). Future studies should identify age- and gender-specific optimal weights and weight-loss strategies for preventing AD and investigate potential mechanisms.