Darren M Lipnicki1, John Crawford1, Nicole A Kochan2, Julian N Trollor3, Brian Draper4, Simone Reppermund3, Kate Maston1, Karen A Mather2, Henry Brodaty4, Perminder S Sachdev5. 1. CHeBA (Centre for Healthy Brain Ageing), School of Psychiatry, University of New South Wales, Sydney, NSW, Australia. 2. CHeBA (Centre for Healthy Brain Ageing), School of Psychiatry, University of New South Wales, Sydney, NSW, Australia; Neuropsychiatric Institute, Prince of Wales Hospital, Sydney, NSW, Australia. 3. CHeBA (Centre for Healthy Brain Ageing), School of Psychiatry, University of New South Wales, Sydney, NSW, Australia; Department of Developmental Disability Neuropsychiatry, School of Psychiatry, University of New South Wales, Sydney, NSW, Australia. 4. CHeBA (Centre for Healthy Brain Ageing), School of Psychiatry, University of New South Wales, Sydney, NSW, Australia; Primary Dementia Collaborative Research Centre, School of Psychiatry, University of New South Wales, Sydney, NSW, Australia; Academic Department for Old Age Psychiatry, Prince of Wales Hospital, Sydney, NSW, Australia. 5. CHeBA (Centre for Healthy Brain Ageing), School of Psychiatry, University of New South Wales, Sydney, NSW, Australia; Neuropsychiatric Institute, Prince of Wales Hospital, Sydney, NSW, Australia; Primary Dementia Collaborative Research Centre, School of Psychiatry, University of New South Wales, Sydney, NSW, Australia. Electronic address: p.sachdev@unsw.edu.au.
Abstract
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.
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.
Authors: Nicole A Kochan; David Bunce; Sarah Pont; John D Crawford; Henry Brodaty; Perminder S Sachdev Journal: PLoS One Date: 2017-08-09 Impact factor: 3.240