Ongoing demographic trends will lead to a huge increase in the prevalence of dementia worldwide in the next 35 years if interventions to reduce its incidence are not implemented. There are many challenges to comparing prevalence rates of Alzheimer’s disease and dementia across countries, including differences in cultural interpretations of memory loss in older people, lifestyle factors that reduce motivation for seeking medical attention for dementia, and application of case-finding methods. Differences in age distributions and mortality rates between countries as well as differences in risk factors, such as genes and education, also are important to consider. Despite these differences, an increase in prevalence with age characterized by a doubling in rate every 5 years has been universally observed. Some data also support an increased prevalence in women compared to men, especially in very old age. In the United States, African-Americans are believed to have twice the prevalence of whites, and Hispanics one-and-a-half times the prevalence of whites. This difference may be due in part to the higher prevalence of vascular diseases and lower levels of education in minority populations.
Alzheimer's Disease, Life Course Perspectives on Risk Reduction, 2016, Pages 57-73,