Increased Prevalence of Obesity/Type 2 Diabetes and Lower Levels of Lithium in Rural Texas Counties May Explain Greater Alzheimer's Disease Risk

Background/Objective: To compare Alzheimer's disease (AD) mortality rates and coinciding risk factors in rural and urban Texas populations. Methods: 155 Texas counties were divided into 73 rural and 82 urban areas using the U.S. Census Bureau definition of rurality. Changes in age-adjusted AD mortality across these counties were calculated using a 7-year aggregation model from 2000-2006 and 2009-2015. Data pertaining to gender, race, education, obesity, diabetes, physical inactivity, and lithium concentrations in tap water were also collected from readily available databases. Results: Change in age-adjusted AD mortality was higher in rural counties (9.5 +/- 1.4) versus urban (5.9 +/- 1.1) over the time period examined. Similarly, obesity (30.2 +/- 0.2%), diabetes (11.0 +/- 0.1%), and physical inactivity (29.4 +/- 0.2%) levels were significantly higher in rural populations compared to urban (29.1 +/- 0.2%, 9.7 +/- 0.1%, and 26.7 +/- 0.3, respectively). In contrast, the percent of population with some college education (40.1 +/- 0.7%) was lower compared to urban (29.4 +/- 0.2% and 44.4 +/- 0.9%, respectively). Lithium concentrations in tap water was significantly lower in rural counties compared to urban (63.3 +/- 8.2 and 33.4 +/- 4.7 mu g/L, respectively). No significant differences were observed among females and however, we did find significant differences in the percent of African American and Hispanics. Correlational analysis uncovered a negative association between education status andADmortality over time (r = -0.17). Further analysis controlling for physical inactivity, education, and trace lithium concentrations results in a loss of statistical significance. Conclusions: AD mortality rates are higher in rural counties when compared to urban counties, and this may be linked to greater physical inactivity, obesity, and diabetes, as well as lower trace lithium levels in tap water.