First Blood Test to Help Diagnose Alzheimer's Goes on Sale

The Associated Press reports that a company has begun to sell the first blood test to help diagnose Alzheimer's disease, which has not been approved by the U.S. Food and Drug Administration. C2N Diagnostics' test is not intended for general screening or for asymptomatic people, but for those 60 and older who are having thinking problems and are being assessed for Alzheimer's. The test is not covered by insurance or Medicare, and costs $1,250 with offers discounts determined by income. The procedure measures two types of amyloid particles plus various forms of a protein that indicate whether someone carries a gene that raises the risk for Alzheimer's. These factors are integrated in a formula that includes age, and subjects receive a score suggesting low, medium, or high likelihood of amyloid accumulation in the brain. C2N has not published data on the test's accuracy, although promotional materials cite results comparing it to positron emission tomography (PET) brain scans in 686 people, 60 to 91 years old, with cognitive impairment or dementia. C2N CEO Joel Braunstein said if a PET scan revealed amyloid buildup, the blood test also gave a high likelihood of that in 92 percent of cases and overlooked 8 percent of them. If the scan was negative, the test ruled out amyloid buildup 77 percent of the time — but while the other 23 percent got a positive result, that does not necessarily indicate that the blood test was incorrect.