KING’S COLLEGE LONDON (UK)—An early biomarker of Alzheimer’s disease may be evident in the blood levels of a single protein years before symptoms appear, new research finds.

Comparing blood samples and brain scans of 300 research participants with Alzheimer’s, scientists found that increased levels of a single protein—clusterin—were related to brain shrinkage, severity of memory problems, and a risk of faster memory loss shown on the brain scans many years later.

The findings could lead to the development of a blood test to identify who would benefit from early treatment of the disease and whether treatments were working to delay or prevent brain damage.

Details of the study are published in the Archives of General Psychiatry.

Using the same method in blood samples from volunteers in an ongoing study in the United States, the researchers also showed that increased amounts of clusterin, measured a decade earlier to the brain scans, were linked to higher levels of beta amyloid in the brain.

“A primary goal in Alzheimer’s research is to develop an inexpensive, easily administered test to accurately detect and track the progression of this devastating disease,” says Madhav Thambisetty, formerly of the Institute of Psychiatry at King’s College London and now with the National Institute on Aging, National Institutes of Health in the US.

“Identifying clusterin as a blood biomarker that may be relevant to both the pathology and symptoms of the disease may bring us closer to this goal.”

Increased levels of clusterin was found in the blood of mice with Alzheimer’s, as they were ageing. Under the microscope, they observed clusterin to be surrounding the amyloid plaques in the mice’s brain, indicating that clusterin might work to help protect the brain from amyloid protein.

“Our results add further evidence to the role of clusterin in AD and though not a test in itself we hope these findings will be taken up by other research groups and if confirmed independently, will help us conclude that clusterin levels in blood are truly a marker of disease pathology in patients with AD,” says Simon Lovestone, professor at King’s College London.

“A simple blood test for detecting Alzheimer’s has long been the holy grail for dementia researchers and these new findings edge us closer in the search,” says Rebecca Wood, chief executive of the Alzheimer’s Research Trust.

“Early detection of dementia will be crucial to ensuring the treatments of the future can be given swiftly and when most effective.”

The study was funded by the Alzheimer’s Research Trust, the NIHR, and by the Innovative Medicines Initiative (IMI).

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