The Effect of Diabetes on the Cognitive Trajectory of Older Adults in Mexico and the United States

Objectives: To study the impact of diabetes on the long-term cognitive trajectories of older adults in 2 countries with different socioeconomic and health settings, and to determine whether this relationship differs by cognitive domains. This study uses Mexico and the United States to confirm if patterns hold in both populations, as these countries have similar diabetes prevalence but different socioeconomic conditions and diabetes-related mortality.

Methods: Two nationally representative cohorts of adults aged 50 years or older are used: the Mexican Health and Aging Study for Mexico and the Health and Retirement Study for the United States, with sample sizes of 18,810 and 26,244 individuals, respectively, followed up for a period of 14 years. The outcome is cognition measured as a total composite score and by domain (memory and nonmemory). Mixed-effect linear models are used to test the effect of diabetes on cognition at 65 years old and over time in each country.

Results: Diabetes is associated with lower cognition and nonmemory scores at baseline and over time in both countries. In Mexico, diabetes only predicts lower memory scores over time, whereas in the United States it only predicts lower memory scores at baseline. Women have higher total cognition and memory scores than men in both studies. The magnitude of the effect of diabetes on cognition is similar in both countries.

Discussion: Despite the overall lower cognition in Mexico and different socioeconomic characteristics, the impact of diabetes on cognitive decline and the main risk and protective factors for poor cognition are similar in both countries.