Genomic African and Native American Ancestry and 15-Year Cognitive Trajectory: Bambui Study, Brazil.

Objectives: To investigate the association between African and Native American genomic ancestry and long-term cognitive trajectories in admixed Brazilians.
Design: Population-based longitudinal study.
Setting: Bambui-Epigen (Brazil) cohort study.
Participants: Adults aged 60 and older (N=1,215) MEASUREMENTS: Participants were followed from January 1997 to December 2011. Cognitive function was assessed annually using the Mini-Mental State Examination (MMSE), totaling 12,208 measurements. We used linear mixed-effects pattern models to assess MMSE score trajectories. Ancestry was assessed using a genome-wide approach.
Results: After adjustments for covariates, the highest quintile of African ancestry was associated with poorer baseline cognitive performance (β=-0.73, 95% confidence interval (CI)=-1.36 to -0.11) but not with cognitive trajectory. Educational level modified the baseline association between highest African ancestry and cognitive performance in that the association was observed only in those with very low (<4 years) education (β=-1.13, 95% CI=-2.02 to -0.23). No association was found between Native American ancestry and baseline cognitive function or its trajectory.
Conclusion: Genomic African and Native American ancestry levels had no prognostic value for age-related cognitive decline in this admixed population.
(© 2018, Copyright the Author Journal compilation © 2018, The American Geriatrics Society.)