Diagnosing Alzheimer’s disease currently relies on cognitive exams and the observation of symptoms, followed by a brain scan or spinal tap to look for the buildup of beta-amyloid protein. A study published in the Journal of the American Medical Association involving more than 1,200 Swedish patients with memory complaints showed promise for a blood test diagnosis, which would be easier and less costly to administer. 

Participants received an initial diagnosis by a primary care physician or specialist doctor and then got the blood test—which is developed by C2N Diagnostics (C2ND) and measures the buildup of tau proteins—as well as a confirming brain scan or spinal tap. While the doctors’ initial diagnoses were 61 percent (primary care) and 73 percent (specialist) accurate, the C2ND blood test proved to be 91 percent accurate. Approval by the U.S. Food and Drug Administration is in the works for this and other competing blood tests.