Four key predictors of dementia identified
Australian researchers have identified four core risk factors for dementia in older people with normal cognition.
Their study followed more than 870 cognitively normal Sydney residents aged 70 and over for six years, during which around 10% developed dementia and 13% died.
They found that along with increasing age, factors predicting a dementia diagnosis included the following:
- Mild cognitive impairment at baseline
- Poorer smelling ability
- Slower walking speed
- Being a carrier of the APOE4 allele.
The researchers from the University of NSW found reversion to normal cognition in people with mild impairment was common, but that these people were still at greater risk of dementia.
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They said poorer smelling ability could predict dementia because Alzheimer’s pathology tended to be present in the olfactory system, even in the preclinical stages of the disease.
Walking speed depended on multiple physical and central nervous systems, and was a marker for general health, they added.
The APOE4 allele was a known risk factor for Alzheimer’s – around 20% of the population carry it and it confers a 3-12 times greater risk of the disease, according to latest research.
Surprisingly, in this study there were lower odds of later dementia in people with diabetes and those with high cholesterol.
The diabetes finding might be due to the effect of taking diabetes medications, lowering glucose levels or enhancing insulin signalling in the brain, the researchers said.
Dementia screening should include testing for poor smell and slow walking speed, according to the study findings, and people who had reverted back from impairment to normal cognition might still need monitoring.