Fitness Fatness Index and Alzheimer-specific mortality

We evaluated the specific association between a Fitness Fat Index (FFI) and Alzheimer's-specific mortality among a national sample of the broader U.S. adult population.

FFI was calculated as cardiorespiratory fitness (CRF) divided by waist-to-height ratio (WHR). Data from the 1999-2006 National Health and Nutrition Examination Survey (NHANES) were used to identify 16,146 participants, ages 20-85. Data from participants in these cycles were linked to death certificate data from the National Death Index. Person-months of follow-up were calculated from the date of the interview until date of death or censoring on December 31, 2011, whichever came first.

In a Cox proportional hazard model, for every 1 FFI unit increase, participants had a 14% reduced hazard of Alzheimer-specific death (HR=0.86; 95% CI: 0.83-0.90; P<0.001). When including diabetes and hypertension (via physician-diagnosis) as covariates, results were unchanged (HR=0.87; 95% CI: 0.82-0.91; P<0.001). Results were also unchanged when restricting the sample to those 50+years (HR=0.92; 95% CI: 0.88-0.97; P=0.005) or stratifying by men (HR=0.85; 95% CI: 0.81-0.91; P<0.001) or women (HR=0.86; 95% CI: 0.79-0.94; P=0.002).

In this national sample of individuals at risk for Alzheimer's disease, increased FFI was associated with reduced risk of Alzheimer's-specific death. Thus, a more favorable fitness-to-fatness ratio is associated with reduced risk of Alzheimer's-specific mortality, underscoring the importance of fitness promoting and fatness reducing strategies.