Risk factors for mild cognitive impairment, dementia and mortality: the Sydney memory and ageing study

Darren M. Lipnicki, John Crawford, Nicole A. Kochan, Julian N. Trollor, Brian Draper, Simone Reppermund, Kate Maston, Karen A. Mather, Henry Brodaty, Perminder S. Sachdev, Sydney Memory and Ageing Study Team

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)


Background: The nature and commonality of late-life risk factors for mild cognitive impairment (MCI), dementia, and mortality remain unclear. Our aim was to investigate potential risk factors, simultaneously in a single cohort including many individuals initially with normal cognition and followed for 6 years. Methods: We classified 873 community-dwelling individuals (70–90 years old and without dementia at baseline) from the Sydney Memory and Ageing Study as cognitively normal (CN), having MCI or dementia, or deceased 6 years after baseline. Associations with baseline demographic, lifestyle, health, and medical factors were investigated, including apolipoprotein (APOE) genotype, MCI at baseline, and reversion from MCI to CN within 2 years of baseline. Results: Eighty-three (9.5%) participants developed dementia and 114 (13%) died within 6 years; nearly 33% had MCI at baseline, of whom 28% reverted to CN within 2 years. A core set of baseline factors was associated with MCI and dementia at 6 years, including older age (per year: odds ratios and 95% confidence intervals = 1.08, 1.01–1.14 for MCI; 1.19, 1.09–1.31 for dementia), MCI at baseline (5.75, 3.49–9.49; 8.23, 3.93–17.22), poorer smelling ability (per extra test point: 0.89, 0.79–1.02; 0.80, 0.68–0.94), slower walking speed (per second: 1.12, 1.00–1.25; 1.21, 1.05–1.39), and being an APOE ε4 carrier (1.84, 1.07–3.14; 3.63, 1.68–7.82). All except APOE genotype were also associated with mortality (age: 1.11, 1.03–1.20; MCI: 3.87, 1.97–7.59; smelling ability: 0.83, 0.70–0.97; walking speed: 1.18, 1.03–1.34). Compared with stable CN participants, individuals reverting from MCI to CN after 2 years were at greater risk of future MCI (3.06, 1.63–5.72). Those who reverted exhibited some different associations between baseline risk factors and 6-year outcomes than individuals with stable MCI. Conclusion: A core group of late-life risk factors indicative of physical and mental frailty are associated with each of dementia, MCI, and mortality after 6 years. Tests for slower walking speed and poorer smelling ability may help screen for cognitive decline. Individuals with normal cognition are at greater risk of future cognitive impairment if they have a history of MCI.

Original languageEnglish
Pages (from-to)388-395
Number of pages8
JournalJournal of the American Medical Directors Association
Issue number5
Publication statusPublished - 1 May 2017
Externally publishedYes


  • mild cognitive impairment
  • dementia
  • mortality
  • risk factors
  • reversion to normal


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