Mild cognitive impairment in Aboriginal Australians

Hannah Derrig; Louise M Lavrencic; Gerald A Broe; Brian Draper; Robert G Cumming; Gail Garvey; Thi Yen Hill; Gail Daylight; Simon Chalkley; Holly Mack; Danielle Lasschuit; Kim Delbaere; Kylie Radford

doi:10.1002/trc2.12054

Mild cognitive impairment in Aboriginal Australians

Alzheimers Dement (N Y). 2020 Aug 24;6(1):e12054. doi: 10.1002/trc2.12054. eCollection 2020.

Authors

Hannah Derrig¹, Louise M Lavrencic^{1

2

3}, Gerald A Broe^{1

2

3}, Brian Draper^{1

2

4}, Robert G Cumming⁵, Gail Garvey⁶, Thi Yen Hill^{1

4}, Gail Daylight¹, Simon Chalkley¹, Holly Mack⁷, Danielle Lasschuit^{1

4}, Kim Delbaere^{1

2

3}, Kylie Radford^{1

2

8}

Affiliations

¹ Neuroscience Research Australia Sydney New South Wales Australia.
² UNSW Ageing Futures Institute University of New South Wales Sydney Australia.
³ School of Public health and Community Medicine University of New South Wales Sydney New South Wales Australia.
⁴ Prince of Wales Hospital Randwick New South Wales Australia.
⁵ School of Public health University of Sydney Sydney New South Wales Australia.
⁶ Menzies School of Health Research Brisbane Queensland Australia.
⁷ University of Technology Sydney Sydney New South Wales Australia.
⁸ School of Medical Sciences University of New South Wales Sydney New South Wales Australia.

Abstract

Introduction: Aboriginal Australians have among the highest rates of dementia worldwide, yet no study has investigated the subtypes, risk factors, or longer term outcomes of mild cognitive impairment (MCI) in this population.

Methods: A total of 336 community-dwelling Aboriginal Australians aged ≥60 years participated in a longitudinal study, completing a structured interview at baseline. MCI (amnestic subtype, aMCI; non-amnestic subtype, naMCI) and dementia were diagnosed via cognitive screening, medical assessment, and clinical consensus. Associations between life-course factors and baseline MCI subtypes were examined using logistic regression. Conversion to dementia was assessed at 6-year follow-up.

Results: Prevalent aMCI (n = 24) was associated with older age (odds ratio [OR] = 1.68, 95% confidence interval [CI]: 1.12 to 2.53), head injury (OR = 3.19, 95% CI: 1.35 to 7.56), symptoms of depression (OR = 1.52, 95% CI: 1.04 to 2.24), and lower blood pressure (OR = 0.53, 95% CI: 0.33 to 0.86). Prevalent naMCI (n = 29) was associated with low education (OR = 4.46, 95% CI: 1.53 to 13.05), unskilled work history (OR = 5.62, 95% CI: 2.07 to 13.90), higher body mass index (OR = 1.99, 95% CI: 1.30 to 3.04), and moderate to severe hearing loss (OR = 2.82, 95% CI: 1.06 to 7.55). A small proportion of MCI cases reverted to intact at follow-up (15%), but most remained stable (44%), developed dementia and/or died (41%).

Discussion: Sociodemographic and clinical factors both contributed to baseline MCI and were distinct for MCI subtypes, with similar patterns of conversion to dementia for amnestic and non-amnestic MCI.

Keywords: Alzheimer's disease; Indigenous; aboriginal Australians; diagnostic stability; mild cognitive impairment; mild cognitive impairment subtypes; predictive validity; risk factors.