Epidemiologic data suggests that certain communities in Africa and Asia may have a lower risk for AD when compared to western countries.

Nearly 25% of community-dwelling African-Americans aged 65 or older in Indianapolis had measurable cognitive problems.  Fewer than half that many, when controlled for age, presented symptoms in Ibadan, Nigeria (Unverzagt et al 2001).

Rates increase among Japanese populations who have emigrated to the US.

All of these suggest that lifestyle factors greatly impact the risk of developing AD.