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A company has started selling the first blood test to help diagnose Alzheimer’s disease, a leap in the field that could make it easier for people to know if they have dementia. It also raises concerns about the accuracy and impact of such life-altering news.
Independent experts are suspicious because key test results have not been published and the test has not been approved by the US Food and Drug Administration (FDA); It is sold under more general rules for commercial laboratories. But they agree that a simple test that can be performed in a doctor’s office has long been needed.
It could have saved Tammy Maida a decade of pointless trips to doctors who attributed her symptoms to depression, anxiety or menopause before a $ 5,000 brain scan last year finally showed she had Alzheimer’s.
“Now I have an answer,” said the 63-year-old former nurse from San Jose, California.
If a blood test had been available, “I might have been scared of the results” but would have “jumped on that” to find out, he said.
More than five million people in the United States and millions more around the world have Alzheimer’s, the most common form of dementia. To be diagnosed with it, people must have symptoms such as memory loss plus evidence of a build-up of a protein called beta-amyloid in the brain.
The best way now to measure protein is an expensive PET brain scan that is generally not covered by insurance. That means most people don’t have one and wonder if their problems are due to normal aging, Alzheimer’s, or something else.
The C2N Diagnostics of St. Louis blood test aims to fill that gap. The founders of the company include Drs. David Holtzman and Randall Bateman of the Washington University School of Medicine, who led the research that led to the trial and are included in a patent that St. Louis University licensed to C2N.
About the test
The test is not designed for general screening or for people without symptoms; is for people 60 years of age and older who have trouble thinking and are being evaluated for Alzheimer’s disease. It is not covered by insurance or Medicare; the company charges $ 1,250 and offers discounts based on income. Only doctors can request the test and results are received within 10 days. It is sold in every state in the US except a few, and has just been licensed for sale in Europe.
It measures two types of amyloid particles plus various forms of a protein that reveal whether someone has a gene that increases the risk of getting the disease. These factors are combined into a formula that includes age, and patients receive a score that suggests a low, medium, or high probability of having amyloid accumulation in the brain.
If the test puts them in the low category, “it’s a compelling reason to look for other things” besides Alzheimer’s, Bateman said.
“There are thousands of things that can cause someone to have cognitive decline,” from vitamin deficiencies to medications, Holtzman said.
“I don’t think this is any different than the tests we do now,” except that it involves a blood test rather than a brain scan, he said. “And those aren’t 100 percent accurate either.”
Accuracy claims
The company has not released any data on the accuracy of the test, although doctors have published on the amyloid research that led to the test. The company’s promotional materials cite results comparing the test to PET brain scans, the current gold standard, in 686 people, ages 60 to 91, with cognitive impairment or dementia.
If a positron emission tomography scan showed amyloid buildup, the blood test also showed a high probability that this occurred in 92 percent of cases and missed 8 percent of them, the company’s chief executive said, Dr. Joel Braunstein.
If the PET scan was negative, the blood test ruled out amyloid buildup 77 percent of the time. The other 23 percent tested positive, but that doesn’t necessarily mean the blood test was wrong, Braunstein said. Published research suggests that it can detect amyloid buildup before it’s evident on scans.
Braunstein said the company will seek FDA approval and the agency has given it a designation that may expedite the review. He said the study results would be released and defended the decision to start selling the test now.
“Should we retain that technology when it could have a big impact on patient care?” I ask.
(Cover image via AP)
