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Blood tests offer clue to dementia risk

Blood tests using biomarkers could be used to predict dementia risk

Blood tests using biomarkers could be used to predict dementia risk

Picture: Alamy

Scientists have developed blood tests that can predict dementia risk. The importance of blood-based biomarkers is that they can improve the identification of people at greatest risk of dementia through low-cost and minimally invasive screening.

These people can then be included in future trials to find ways to prevent the development of dementia.

The aim of this study was to investigate the use of plasma total tau as a blood biomarker for dementia and related endophenotypes – cognitive or physiological characteristics that can be measured but are not visible and may be detectable even if the disease is not present.

This prospective cohort study used data from the US community-based Framingham Heart Study. Researchers studied data from a subgroup of people with mild cognitive impairment or subjective cognitive complaints.

Plasma or cerebrospinal fluid samples, or both, had been taken at the start of the study. Dementia follow-up occurred after three to eight years in people over the age of 65 who were free of dementia at baseline. The researchers looked for dementia of any cause and for dementia related to clinical Alzheimer’s disease.

Minimally invasive

The results showed that higher plasma total tau level was associated with poorer cognition across seven cognitive tasks. Post-mortem examination of the brain showed that those with higher levels of plasma total tau also had smaller hippocampi and the neurofibrillary tangles associated with Alzheimer’s disease.

The results from plasma samples were at least as strongly associated with the development of Alzheimer’s disease as samples of cerebrospinal fluid, suggesting that minimally invasive blood tests may be useful as a biomarker for risk.

Ruth Sander is an independent consultant in the care of older people

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