Indigenous peoples represent up to 5% of the world's population (almost 400 million people), representing thousands of individual cultures and language groups. The health status of older Indigenous peoples has been little researched, partly related to lower life expectancy and the consideration that Indigenous peoples do not live long enough to experience the common “geriatric syndromes” such as dementia, frailty, and falls. Statistics from Australia and Canada now report that Indigenous populations are undergoing rapid aging, with many examples of survivorship to old age (Arkles et al., Reference Arkles, Jackson Pulver, Robertson, Draper, Chalkley and Broe2010; Jacklin et al., Reference Jacklin, Walker and Shawande2012). The systematic review by Warren et al. (Reference Warren, Qiyun, Young, Borenstein and Martiniuk2015) is a timely one, in that it reminds clinicians interested in old age that this “fourth” World population deserves further attention. Researchers that have worked with these groups to produce population estimates are relatively few. In their systematic review, Warren et al. (Reference Warren, Qiyun, Young, Borenstein and Martiniuk2015) demonstrate wide variation in prevalence rates of dementia. They conclude that a major cause of this heterogeneity in prevalence is due to basic methodological differences. In particular, those studies that have utilized already acquired routine data may be biased. The type and direction of this bias can be complex. For example, Cotter et al. (Reference Cotter, Condon, Barnes, Anderson, Smith and Cunningham2012) using routinely collected data, concluded that the prevalence of dementia in Aboriginal Australians in the Northern Territory was not higher than non-Aboriginal prevalence. Using similar methodologies some years later the conclusion was that the Aboriginal population had markedly higher rates (Li et al., Reference Li2014). In the intervening period, a dementia awareness campaign coupled with the development of a culturally appropriate screening tool probably resulted in greater detection in routine care.

Even amongst those studies that directly assessed participants there was still major variation in prevalence, for example, Hendrie in the 1990s reported low rates of dementia in Cree Indians after adjustment for common confounding factors (Hendrie et al., Reference Hendrie1993), whilst recent Australian data demonstrated higher rates of dementia up to 3–4 times the average populations in both urban and rural areas, with presenting symptoms at an earlier age (Radford et al., Reference Radford2014; LoGiudice et al., Reference LoGiudice2015). These studies utilized culturally adapted assessments and representative population samples. Perhaps the differences between these studies arose because frailer members of the Cree community often left the reservation and were unable to be assessed, whereas in the Australian studies approximately half of the people with dementia were interviewed in regional nursing homes. Supporting more recent data, a study of Indigenous Malaysians reported similarly high rates of dementia (Pu’un et al., Reference Pu’un, Othman and Drahman2014).

The definition of Indigenous is complex, although common features that characterize these groups include poor socioeconomic factors, high rates of diseases linked to poor lifestyle factors (e.g. low physical activity, smoking, alcohol use, poor education) and early death. Conditions such as diabetes, hypertension, obesity, and renal impairment are rife, and physical trauma, especially head injuries, are common. Underpinning these damning statistics is often a history of colonization, racism and intergenerational trauma that has impacted on traditional lifestyles over generations. Therefore, the risk factors that are increasingly acknowledged as predictors of dementia and cognitive impairment are abundant in these communities and begin early after conception (Drachmann, Reference Drachman2006). The few studies that have characterized types of dementia demonstrate Alzheimer's Disease as a major contributing cause. Social and environmental factors play a dominant part, with multifactorial causes likely to be common. Possible genetic factors as yet to be described may interact with this complex mix of factors. The study of Indigenous peoples worldwide may provide important knowledge and guidance for non-Indigenous people. The high prevalence of dementia probably reflects major environmental differences, e.g. amount and type of education, dietary factors, physical activity, social engagement, and others. These factors play an important role for all populations and argue against a unidimensional biological approach to the prevention of Alzheimer's Disease and dementia.

Cross national studies to address this emerging issue is important for policy and planning. Dementia awareness in communities will need to be provided in a culturally appropriate manner. Common myths suggesting that dementia is not likely to occur in Indigenous communities due to poor life expectancy, and is largely due to high alcohol consumption have been debunked. Provision of care taking into consideration diverse languages and traditions will need to consider the whole community and not only individuals and carers. Risk factor prevention needs to highlight the benefits of cognitive health, and accompanying positive outcomes on other common co-morbid conditions. There is increasing interest worldwide on the topic of dementia in Indigenous older people, with population based studies being conducted on aging in New Zealand, Canada, and other countries such as Brazil, that will continue to provide important insights on this issue worldwide, not only to benefit Indigenous communities but deepen our understanding of the causes of dementia for everyone.