> a smaller percentage of Tsimané survive to the age at which Alzheimers becomes a major epidemiological issue in modern societies. How does a researcher accoun

> a smaller percentage of Tsimané survive to the age at which Alzheimers becomes a major epidemiological issue in modern societies. How does a researcher account for that? It seems like it could be a confounder. This would be an issue if Alzheimers is part of a phenotype that raises all-cause mortality in the young. I'm not aware of any research on this. Alzheimers is known to be correlated with certain lifestyle and immune factors, and these factors might be expressions of a common phenotype that also increases early mortality and is moderated by pre-industrial environments---e.g. increased risk-taking or decreased immunity. A common phenotype hypothesis might explain some of the difference in Alzheimers incidence between Tsimane and Westerners, but it would be surprising if it were the main reason. Assuming the hypothesis only, an Alzheimers delta of 11x for those over 65 implies a mortality rate delta of 11x between the under-65 phenotype groups. That is a massive effect, and if it includes child mortality, we would expect to see genetic drift over time and a lower genetic predisposition to Alzheimers among Tsimane (has that been studied?).