Prevalence and incidence of dementia among indigenous populations: a systematic review

Background: Indigenous populations may be at increased risk, compared with majority populations, for the development of dementia due to lower education levels and socio-economic status, higher rates of diabetes, hypertension, cardiovascular disease and alcohol abuse, an aging population structure, and poorer overall health. This is the first systematic review investigating the prevalence and incidence of dementia in indigenous populations worldwide.

Methods: This systematic review was conducted in accordance with PRISMA guidelines. We searched MEDLINE, Embase, and PsycInfo for relevant papers published up to April 2015. Studies were included if they reported prevalence or incidence, the disease typically occurred after the age of 45, the study population included indigenous people, and the study was conducted in the general population.

Results: Fifteen studies representing five countries (Canada, Australia, the USA, Guam, Brazil) met the inclusion criteria. Dementia prevalence ranged from 0.5% to 20%. Retrospective studies relying on medical records for diagnoses had much lower prevalence rates and a higher risk of bias than population-based prospective studies performing their own diagnoses with culturally appropriate cognitive assessment methods.

Conclusions: The prevalence of dementia among indigenous populations appears to be higher than it is for non-indigenous populations. Despite a building body of evidence supporting the need for dementia research among indigenous populations, there is a paucity of epidemiological research, none of which is of high quality.