Dementia in Aboriginal Australians

Abstract

The Kimberley Region of Australia is an exceptional environment. It is three times the size of England but is inhabited by only 33,000 people. Its Aboriginal popula-tion speak in 30 different languages with English often as a third or fourth language, with low levels of literacy. They live in remote rural communities and small towns. In the Wet, the consistent temperature is around 38 ° to 40 ° C. Kimberley people are generally representative of more remote and distant-rural Aboriginal people who make up some 30% of the total Aboriginal population. However, around 70% of Australian Aboriginal people live in non-remote cities, urban settings or rural towns; the large majority of these are English speaking and liter-ate with at least basic schooling. Aboriginal Australians, both remote and urban, face profound socio-economic and educational disadvantage, trauma and stress com-pared to the non-Indigenous population. From Australian Bureau of Statistics data, health outcomes are equally poor and life expectancy reduced in both remote and urban settings and poorer than those in other Indigenous cultures within developed nations. In a previous paper, Smith and her colleagues found the prevalence of dementia by DSM-IV criteria to be 27% in the Aboriginal elderly aged over 65 years [1]. This estimate is fi ve times higher than the overall Aus-tralian population after age standardisation. In this issue, they now report their fi ndings on risk factors. The study is a remarkable achievement in its own right. There must have been many diffi culties in obtain-ing the fi ndings. Each of these diffi culties raises ques-tions when it comes to their interpretation. Accurate case ascertainment required fi rstly the identifi cation of the denominator of elderly individuals in communities where a person ’ s age is often not known, conducting an appro-priate clinical examination, and then obtaining clinically relevant information from informants. The latter might often be reluctant to portray older individuals as impaired in behaviour. There is then the crucial matter of applying diagnostic criteria that are valid for this group of Aborig-inal elderly. Importantly, the authors have previously validated their screening instrument (the KICA Cog) for this remote Aboriginal population with low literacy and English often a second language, using clinical assess-ment by geriatricians and psychiatrists experienced in dementia diagnosis and they have used this methodology in the current study [2]. When it comes to measuring exposure to risk factors, the authors have appropriately limited this initial survey to key demographic, lifestyle and clinical factors using culturally adapted instruments. The study has therefore been a major undertaking in the epidemiology of demen-tia. We now examine the signifi cance of the fi ndings both on prevalence and risk factors. Firstly, the strikingly high prevalence estimate calls for interpretation. The study was apparently not constrained by having any hypotheses before data collection started. It is unknown whether the investigators expected to fi nd higher or lower rates than in elderly Caucasians. Cases were ascertained in a two-phase design using their KIKA screening instrument. This was followed by reaching a diagnosis through clinical consensus, made by two specialists applying DSM-IV criteria. These criteria are now considered by some to have limitations for non-western populations because of the primacy accorded to memory impairment and their lack of operational defi nition. According to Prince