Could a blood test detect Alzheimer disease?



According to Pedro Rosa-Neto and Serge Gauthier, professors in the departments of Neurology and Neurosurgery and Psychiatry at McGill University and researchers at the Douglas Research Centre, it may be possible to accurately diagnose Alzheimer disease (AD) long before any symptoms appear and virtually painlessly by taking a simple blood sample. In collaboration with scientific experts in Canada and Sweden, they identified a blood biomarker that reveals the tau protein that distinguishes AD from other types of dementia.

AD is currently detected on the basis of clinical signs, including progressive memory loss.

Over 125 000 Quebecers suffer from Alzheimer disease or another neurodegenerative disease. AD is currently detected on the basis of clinical signs, including progressive memory loss. The diagnosis is then confirmed by a positron emission tomography (PET) scan—an expensive medical imaging technique that measures the accumulation of amyloid and tau proteins in the brain. Alternatively, the results of a lumbar puncture, a somewhat uncomfortable procedure, also make it possible to sample the biomarkers of the two proteins that cause neuronal damage.

The blood test was developed thanks to the participation of 400 Quebecers with an average age of 70 years old and mild cognitive impairments, which are among the early signs of AD. The participants were selected from the Translational Biomarkers in Aging and Dementia (TRIAD) cohort led by Pedro Rosa-Neto and Serge Gauthier. The seniors have been studied for the past four years in an effort to determine the molecular processes that trigger symptoms and biomarkers of the disease.

The researchers are now working to validate the results with those of other cohorts to ultimately eliminate the need for scans and lumbar punctures. In addition to being highly accurate, the blood test is less costly and invasive than the current alternatives.