Researchers pinpoint blood biomarker that foretells dementia

Researchers from the National University of Ireland, Galway (NUI Galway) and Boston University have identified a blood biomarker that could help diagnose people with the earliest signs of dementia––even before symptoms appear.

“Dementia,” according to the Alzheimer's Association, “is a general term for loss of memory, language, problem-solving and other thinking abilities that are severe enough to interfere with daily life. Alzheimer's is the most common cause of dementia.”

The Mayo Clinic defines dementia as “caused by damage to or loss of nerve cells and their connections in the brain. Depending on the area of the brain that's damaged, dementia can affect people differently and cause different symptoms.”

The new study was published in the Journal of Alzheimer’s Disease.

The researchers took blood samples from people who had no cognitive symptoms and who had normal cognitive testing at the time of blood testing, a news release explains. They measured blood levels of P-tau181, a protein that happens to be a marker of neurodegeneration, in 52 cognitively healthy adults. These 52 adults from the US-based Framingham Heart Study were later subjected to specialised brain PET scans.

Researchers showed an association with elevated levels of P-tau181 protein in the blood with greater accumulation of ß-amyloid  [amyloid beta precursor protein], an abnormal protein in Alzheimer’s disease, on specialised brain scans. The specialised brain scans were carried out on average seven years after the blood test.

Further analysis, the release noted, showed the biomarker P-tau181 “outperformed two other biomarkers in predicting signs of ß-amyloid on brain scans”.

“The amyloid-beta precursor protein…is a large membrane protein that normally plays an essential role in neural growth and repair. However, later in life, a corrupted form can destroy nerve cells, leading to the loss of thought and memory in Alzheimer's disease,” explains Protein Data Bank (PDB).

The lead author of the study was Emer McGrath, Associate Professor at the College of Medicine Nursing and Health Sciences at NUI Galway and Consultant Neurologist at Saolta University Health Care Group.

“The results of this study are very promising - P-tau181 has the potential to help us identify individuals at high risk of dementia at a very early stage of the disease, before they develop memory difficulties or changes in behaviour,” Professor McGrath says.

The research team suggests that the identification of a biomarker for Alzheimer’s disease could potentially pave the way for a population screening programme.

Professor McGrath says: “This study was carried out among people living in the community, reflecting those attending GP practices. A blood test measuring P-tau181 levels could potentially be used as a population-level screening tool for predicting risk of dementia in individuals at mid to late-life, or even earlier.

 “This research also has important potential implications in the context of clinical trials. Blood levels of P-tau181 could be used to identify suitable participants for further research, including in clinical trials of new therapies for dementia,” Mc Grath adds. “We could use this biomarker to identify those at a high risk of developing dementia but still at a very early stage in the disease, when there is still an opportunity to prevent the disease from progressing.”