Dementia Incidence, APOE Genotype, and Risk Factors for Cognitive Decline in Aboriginal Australians: A Longitudinal Cohort Study

Louise M. Lavrencic, Kim Delbaere, Gerald A. Broe, Gail Daylight, Brian Draper, Robert G. Cumming, Gail Garvey, Wendy Allan, Thi Yen Hill, Danielle Lasschuit, Peter R. Schofield, Kylie Radford

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND AND OBJECTIVES: Aboriginal Australians are disproportionately affected by dementia, with incidence in remote populations approximately double that of non-Indigenous populations. This study aimed to identify dementia incidence and risk factors in Aboriginal Australians residing in urban areas, which are currently unknown. METHODS: A population-based cohort of Aboriginal Australians ≥60 years of age was assessed at baseline and 6-year follow-up. Life-course risk factors (baseline) were examined for incident dementia or mild cognitive impairment (MCI) through logistic regression analyses; adjustments were made for age. APOE genotyping was available for 86 people. RESULTS: Data were included from 155 participants 60 to 86 years of age (mean 65.70 years, SD 5.65 years; 59 male). There were 16 incident dementia cases (age-standardized rate 35.97/1,000 person-years, 95% confidence interval [CI] 18.34-53.60) and 36 combined incident MCI and dementia cases. Older age (odds ratio [OR] 2.29, 95% CI 1.42-3.70), male sex (OR 4.14, 95% CI 1.60-10.77), unskilled work history (OR 5.09, 95% CI 1.95-13.26), polypharmacy (OR 3.11, 95% CI 1.17-8.28), and past smoking (OR 0.24, 95% CI 0.08-0.75) were associated with incident MCI/dementia in the final model. APOE ε4 allele frequency was 24%; heterozygous or homozygous ε4 was associated with incident MCI/dementia (bivariate OR 3.96, 95% CI 1.25-12.50). DISCUSSION: These findings provide evidence for higher dementia incidence in Aboriginal Australians from urban areas, where the majority of Aboriginal people reside. This study also sheds light on sociodemographic, health, and genetic factors associated with incident MCI/dementia at older ages in this population, which is critical for targeted prevention strategies.

Original languageEnglish
Pages (from-to)e1124-e1136
Number of pages13
JournalNeurology
Volume98
Issue number11
DOIs
Publication statusPublished - 15 Mar 2022

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