RESUMEN
BACKGROUND: Alzheimer's disease (AD) is the most common form of dementia worldwide, and bears remarkable evidence for a differential prevalence among continental populations. In this scenario, estimating ancestry proportions in recently admixed populations is a strategy that can help increasing knowledge about the genetic structure of this complex trait. AIM/METHODS: Our purpose was to assess mean ancestry estimates for the three main parental contributors to the Brazilian contingent (European, African and Amerindian) using a panel of 12 ancestry informative markers. Outpatients with the late-onset form of AD (n = 120) were compared for ancestry levels with non-cognitively impaired subjects (n = 412) in the Midwest Brazil, controlling for classic clinical, social and anthropometric risk factors. RESULTS: Our findings show a 3-fold greater genetic Amerindian content among control subjects compared to AD patients (p < 0.001). CONCLUSION: Our results suggest that the allelic architecture of Native Americans can confer protection against the onset of the disease.