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Alzheimer's Disease Diagnostics

Key Alzheimer's Marker Identified in Blood Test

4 months, 3 weeks ago

3142  0
Posted on Jul 20, 2017, 8 a.m.

Study findings are a significant step in predicting Alzheimer's Disease years before one could be diagnosed based on symptoms.

Washington University School of Medicine researchers recently conducted a study that determined an amyloid beta test of blood may help identify individuals who are at risk for Alzheimer’s disease. The goal is for a blood-based screening to pinpoint those who have begun to develop the biological predecessors to Alzheimer’s years before actually being diagnosed with symptoms of the disease.

The Path Toward Alzheimer’s

The brains of those who eventually develop Alzheimer’s disease are marked with plaques consisting of a sticky protein referred to as amyloid beta. Medical professionals believe this protein is a primary contributor to the disease and its gradual progression. Such amyloid beta plaques appear within the brain decades before Alzheimer’s patients endure regular confusion and memory loss. At the moment, the only means of detecting amyloid beta is through PET scanning. Unfortunately, PET scanning is costly and not available to the masses. Though it is possible to identify amyloid beta through a spinal tap, such a procedure is quite invasive.

When the brain is put to use to complete daily tasks, it regularly generates and clears amyloid beta. A portion of this protein is washed into the blood. Some of it floats into the cerebrospinal fluid. Yet if amyloid beta begins to accumulate, it can form into plaques that adhere to neurons and cause neurological damage. The hope is that a blood test would prove to be significantly cheaper and minimally invasive compared to a spinal tap or PET scan. However, it must be noted that aggregate amyloid beta levels within the blood do not always correlate to the protein's levels within the brain.

A Potential Solution

The research team from the Washington University School of Medicine in St. Louis has found that amyloid beta tests of blood might help in the quest to identify those who have altered levels of the protein within their cerebrospinal fluid or brain. The research team's study results show that amyloid beta blood testing really can find out if amyloid has started to accumulate within the brain. This is an important breakthrough as it could serve as the foundation for a fast and low-cost blood screening test that pinpoints those who are at an extremely high risk of developing Alzheimer’s disease down the line.

Study Details

The researchers measured blood levels of three amyloid variations: amyloid beta 42, amyloid beta 40 and amyloid beta 38. They used mass spectrometry to determine if there was a correlation of the levels within the brain. The study analyzed 41 individuals age 60 on up. Slightly more than half of these participants were amyloid-positive. This means they showed signs of mental impairment. They also had amyloid plaques within the brain or alterations of amyloid in their cerebrospinal fluid. There was no amyloid buildup in the brains of 18 participants. The research team drew 20 blood samples from each participant across a 24-hour period.

The Results

The researchers determined levels of amyloid beta 42 in relation to amyloid beta 40 were between 10 and 15 percent less than those in individuals with amyloid plaques. Amyloid plaques are mainly comprised of amyloid beta 42. This means it is deposited within the brain before traveling to the bloodstream. The researchers accurately classified individuals as amyloid-positive or negative nearly 90 percent of the time by comparing the two types of amyloid beta to one another. The hope is that this breakthrough test will identify those who are at an especially high risk for Alzheimer’s. Such individuals can then be proactive in their fight against this crippling disease.

Vitaliy Ovod, Kara N. Ramsey, Kwasi G. Mawuenyega, Jim G. Bollinger, Terry Hicks, Theresa Schneider, Melissa Sullivan, Katrina Paumier, David M. Holtzman, John C. Morris, Tammie Benzinger, Anne M. Fagan, Bruce W. Patterson, Randall J. Bateman. Amyloid β concentrations and stable isotope labeling kinetics of human plasma specific to central nervous system amyloidosis. Alzheimer's & Dementia, 2017; DOI: 10.1016/j.jalz.2017.06.2266

https://medicine.wustl.edu/news/blood-test-ids-key-alzheimers-marker-brain/

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