A simple blood test can identify markers of Alzheimer’s disease before patients begin to experience memory loss and confusion . This discovery represents a giant step toward predicting disease risk. The research, led by scientists at the Washington University School of Medicine in St. Louis (USA), has been published in the journal Alzheimer and Dementia.
For people with Alzheimer’s disease, neuronal loss begins before symptoms of the disease begin to appear . The brain makes and clears a sticky protein called beta amyloid; But, if the protein begins to accumulate, plaques begin to form in the brain and adhere to neurons causing neurological damage, contributing to the development and progression of azheimer.
This is why it is so important to predict the risk of Alzheimer’s well in advance. At present, the only viable methods for the detection of beta amyloid are positron emission tomography (PET) or lumbar puncture. However, PET scanning is expensive and not generally available, and lumbar puncture is highly invasive and few physicians are available to do it.
To overcome these obstacles, the researchers evaluated the levels of beta amyloid in the blood to find out if a blood test could help identify altered levels of the protein in the brain and cerebrospinal fluid.
Specifically, they had the participation of 41 individuals of 60 years of age to evaluate the blood concentration of beta amyloid. 23 people tested positive, showing they had signs of cognitive decline. These participants also had PET scans or lumbar puncture interventions to confirm the presence of amyloid plaques in the brain or amyloid abnormalities in their cerebrospinal fluid.
The scientists took 20 blood samples from each individual (including those who did not test positive for beta amyloid) in the next 24 hours. They found that for those with amyloid plaques, the levels of amyloid beta 42 relative to amyloid beta 40 were around 10-15% lower.
“Amyloid plaques are primarily made up of beta amyloid 42, so it probably means that it is being deposited in the brain before it enters the bloodstream,” explains Randall J. Bateman, leader of the work.
“ The differences are not large, but they are very consistent, our method is very sensitive, and especially when we have many repeated samples as in this study – more than 500 samples in general – we can be sure that the difference is real. A single sample can distinguish who has amyloid plaques, “explains Bateman.
The scientists found they could classify people with 89% accuracy as amyloid-positive or amyloid-negative, based on the ratio of amyloid beta 42 to amyloid beta 40 on each of the participant’s 20 blood samples.
“Our results show that this beta-amyloid can detect whether amyloid has started to build up in the brain, which is exciting because it could be the basis for a quick and inexpensive blood screening test to identify people at high risk of develop Alzheimer’s disease, “concludes Bateman.
Reference: Blood test IDs key Alzheimer’s marker. Washington University School of Medicine. Alzheimer’s and Dementia.
