Alzheimer’s disease is the sixth leading cause of death in the United States, with someone developing the disease almost every minute, according to the Alzheimer’s Association.
For years, scientists have been searching for a reliable blood test that can detect amyloid beta, the protein frequently associated with this life-changing condition.
Now researchers at Washington University in St. Louis, Missouri, say they’ve discovered the potential option for a test.
“Amyloid is a protein normally found in the body that’s involved in brain cell physiology. When there’s a loss of balance between the production of amyloid beta and clearance from the brain, the abnormal accumulation leads to neuronal cell death,” Dr. Diana Kerwin, a geriatrics specialist at Texas Health Dallas, told ishonest.
“Amyloid beta can accumulate at an abnormal rate in the brain and form plaque that’s associated with neuron cell death in the brain and memory loss,” explained Dr. Kerwin, who’s a member of the national board of the Alzheimer’s Association and is the chair of the association’s Dallas chapter.
Alzheimer’s disease is typically diagnosed by detecting memory loss not related to normal aging or to another medical issue or neurologic disease, she said.
“The accuracy of the diagnosis without the addition of specialized scans, with a thorough work up by a primary care physician, can be 70 to 80 percent,” Kerwin said.
“Diagnosis is usually made by clinical examination, brain imaging to rule out other abnormalities, memory testing called neuropsychological testing that determines if there is memory loss that is more than expected for the person’s age and education level, and blood work to rule out other medical illness such as infection or kidney or liver disease that can affect brain function and memory,” she added.
However, a recent study from Washington University in St. Louis, Missouri has concluded that the risk of Alzheimer’s disease can be predicted with 94 percent accuracy when results from a new blood test are combined with two other major risk factors, such as age or family history of the disease.
“This is exciting because it could be the basis for a rapid and inexpensive blood screening test to identify people at high risk of developing Alzheimer’s disease,” he continued.
However, Dr. Anna Tseng, a neurologist at Texas Health Dallas, expressed some need for caution.
“Amyloid plaque is just one of the hallmarks of Alzheimer’s disease, but it isn’t specific to the disease,” she told ishonest. “It can be found in other types of dementia and even in cognitively healthy people.”
Dr. Tseng explained that there are unanswered questions about amyloid’s role in the brain.
“While the function of amyloid protein isn’t known, some studies suggest that it may actually help with immunity,” she noted.
One blood sample could be enough
In their study, researchers used a technique called mass spectrometry to measure amounts of two types of amyloid beta in the blood, called amyloid beta 40 and 42.
They found the ratio of these types in the blood goes down as the amount of the substance in the brain increases.
The study examined 158 adults older than 50, most who were cognitively healthy.
Dr. Bateman and his team reported that even some false positives seen in initial tests still predicted a later buildup of amyloid in the brain, something that was found years later by positron emission tomography (PET) scans.
This suggests the new test can warn of amyloid deposits forming years before they can be identified by PET scans.
“Our method is very sensitive, and particularly when you have many repeated samples as in this study — more than 500 samples overall — we can be highly confident that the difference is real. Even a single sample can distinguish who has amyloid plaques,” he said.
Early detection may allow people to take action to slow down disease progression.
“There are three acetylcholinesterase inhibitors and a drug called memantine that have modest benefits in slowing down the progression of Alzheimer’s disease,” Tseng said. “But following a healthy lifestyle, with exercise and good diet, and maintaining social engagement can help significantly as well.”
Avoiding exposure and expenses
The new blood test could offer a broad range of benefits.
“The test is significantly less expensive than a PET scan and it’s less uncomfortable than a spinal tap. It may help people with early memory concerns to determine if it’s related to abnormal accumulation of amyloid,” Kerwin said. “The test may help to lessen the burden to undergo spinal tap or expensive PET scan that isn’t currently covered by insurance and to reduce the risk of radiation exposure from repeated scans.”
“For researchers this can increase the ability to screen and find people for clinical trials that can reduce the cost of starting a clinical trial and improve the quality of data collection to determine faster if the treatment is of benefit or not,” she added.
“An advancement that helps to more quickly collect good quality data is of benefit to all participants because it will help researchers move treatment developments forward.”
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