The Food and Drug Administration May 16 announced it cleared the first blood test to diagnose Alzheimer’s disease. The test, created by Fujirebio Diagnostics, only requires a blood draw, making it less invasive and easier for patients to access, the agency said. The test measures two proteins in the blood, pTau217 and β-amyloid 1-42, and calculates the numerical ratio between them. The ratio is correlated to the presence or absence of amyloid plaques in the patient’s brain — an indicator of Alzheimer’s. The blood test reduces the need for a positron emission tomography scan.