A core group of late-life risk factors have been identified for mild cognitive impairment (MCI), dementia and mortality by researchers at the Centre for Healthy Brain Ageing (CHeBA), UNSW Sydney. The findings were published in the Journal of the American Medical Directors Association.
The longitudinal study examined changes in cognitive status, particularly the development of MCI or dementia, as well as death, over a six year period for 873 community-dwelling individuals aged 70-90 years in CHeBA's Sydney Memory & Ageing Study (MAS). Baseline factors associated with having MCi and dementia after 6 years were: older age, MCI at baseline, poorer smelling ability, slower walking speed and being an ApoE ε4 carrier, a known genetic risk for Alzheimer's disease. All factors except ApoE ε4 carrier-status were also associated with mortality.
Lead author CHeBA researcher Dr Darren Lipnicki said the findings provided exciting new insights into risk factors to inform early diagnosis and promote healthy ageing.
“Risk factors indicative of physical and mental frailty were significantly associated with dementia, MCI and mortality. This means that relatively straight-forward tests like walking speed and smelling ability may help screen for cognitive decline,” explained Dr Lipnicki.
The study also highlighted the complex relationship between MCI and dementia.
“At the start of the study period, nearly 33% of participants had MCI, of whom 28% reverted to being cognitively normal within two years. Reverters were at greater risk of future MCI than those who were cognitively stable, however reverters also showed different associations between baseline risk factors and six-year outcomes than individuals with stable MCI.”
Unlike those with stable MCI, among reverters older age predicted dementia; a slower six minute walk time predicted each of MCI, dementia, and mortality; and lower BMI and higher cholesterol levels predicted mortality. Interestingly, being a male reverter reduced the likelihood of future MCI.
Co-author and CHeBA Co-Director, Professor Perminder Sachdev, said that large, longitudinal studies like MAS are vital for determining risk factors over time.
“Studies like this highlight the complexity of dementia aetiology, but also that identifying risk factors is possible. At CHeBA, our goal is drawing on both local longitudinal studies and large-scale international cohorts to improve our understanding and, ultimately, inform diagnostic and intervention strategies where possible.”