Population aging has been accompanied by worldwide growth in dementia. However, little is known about the prevalence of dementia and cognitive impairment not dementia in ethnically diverse populations, such as indigenous populations conceptualized as groups of persons who self-identify as indigenous and who are recognized as distinctive communities reproducing ancestral, historical, and territorial culture. This is particularly relevant in view of increasing life expectancy in indigenous populations and, consequently, in the number of elderly people, as well as the changes in their multimorbidity profile. In this study, a systematic review of the literature on the subject "cognitive impairment in indigenous elderly population" in the databases MEDLINE via PubMed, Lilacs, and Scopus showed that the prevalence of dementia in indigenous populations between 45 and 94 years old, originally from different countries, varied between 0.5% and 26.8% for age 60 and older, whereas the prevalence of cognitive impairment not dementia varied between 4.4% and 17.7%. Early onset of the disease, older age, low education level, and several poor health conditions were associated with prevalence rates and conversion from normal to any cognitive impairment. Cultural inadequacy of neuropsychological tests was the main factor reported in the selected studies, which makes the investigation of dementia a challenge in indigenous populations. These data reveal that the prevalence rates of dementia ranged from low to very high for those aged 60 years and older, with early onset of the disease and elevated mortality rate after initial diagnosis compared with the current global prevalence studies, suggesting that these individuals may be more vulnerable to cognitive disorders. Cognitive reserve and exposure to poor health status throughout life span may be considered in the interpretation of results.

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Background Dementia detection in indigenous populations, represents a challenge worldwide, due to the absence of culturally adapted cognitive tests. The Kimberley Indigenous Cognitive Assessment (KICA) was developed and validated to evaluate global cognitive performance in Aboriginal Australians. We aimed to determine reliability and validity of the KICA, and specificity and sensitivity in detecting cognitive impairment in a Brazilian indigenous community. Method The KICA was translated and back translated into Portuguese by independent translators. The translated version was revised by an experts committee and pre‐tested. Healthy indigenous older adults (n=123, Age mean=63.7, SD=±9.1; Education mean=1.5, SD±2.3) and indigenous patients with cognitive impairment (n=94; Age mean=65.0, SD±11.5; Education mean=1.1, SD±11.5) from Amazonas, Brazil, were administered the KICA and Mini‐Mental State Examination (MMSE). Cognitive impairment classification was based on the DSM‐IV and ICD‐10 criteria. The KICA reliability and validity was analyzed using Cronbach's alpha and Pearson correlation coefficient between KICA and MMSE scores. Sensitivity and specificity were calculated at several cutoff values and the area under the Receiver Operator Characteristic (ROC) curve was calculated. Result The KICA demonstrated moderate internal consistency (Cronbach's alpha coefficient=0.787) and was significantly correlated with MMSE scores (r=0.660; p<0.001; Pearson coefficient). The best equilibrium was at the cutoff value of 26/27 out of 39 showing 72% sensitivity and 73% specificity; the area under the ROC curve was 0.78 (95% CI: 0.72‐0.84). Conclusion Our results indicate that the KICA is a reliable tool and can be used for screening cognitive impairment in Brazilian indigenous with low education background.

ABSTRACT. Studies on the prevalence of dementia in the indigenous population are still scarce worldwide. In the few available studies, prevalence evidence varies from low to very high, with early onset of the disease and high mortality rate after the initial diagnosis. Still, little is known about the rate of dementia in indigenous populations from low- and middle-income countries, where the dementia prevalence in the general population is estimated to increase significantly in the next decades. Objective: This study aimed to determine the prevalence of cognitive impairment and associated factors in Brazilian indigenous people of the Mura ethnicity in Amazonas, Brazil. Methods: A total of 217 indigenous individuals aged 50 years and older from Amazonas, Brazil, were submitted to cognitive assessment. Attention, memory, verbal fluency, visuospatial performance, and mood state composed the cognitive impairment diagnosis. Results: The prevalence of cognitive impairment was 43.3% (95%CI 36.6-49.7) and varied according to age [OR=1.03 (95%CI 1.00-1.06)], education [OR=0.74 (95%CI 0.62-0.87)], body mass index [OR=0.91 (95%CI 0.83-0.98)], and income [OR=0.52 (95%CI 0.27-0.99)]. Conclusions: Cognitive impairment had an early onset in an indigenous community, and its prevalence was greater in older individuals with low education and low family income. These findings highlight the importance of implementing public indigenous health policies focusing on health professional training for early cognitive impairment detection.