Blood tests needed for widespread Alzheimer's diagnosis on the way

investing.com:

By Deena Beasley

(Reuters) — Blood tests for Alzheimer's are needed to more widely diagnose the brain-wasting disease and understand its prevalence, but it will be another couple of years before they become an everyday tool, medical experts and company executives say.

Blood testing is initially likely to be used to rule out Alzheimer's, with positive results signaling the need for more advanced diagnostics.

Several Alzheimer's blood tests are in the works – and one is already being sold to consumers – but none have been established as accurate, formally approved by regulators or reimbursed by insurers. Some are being used to help screen participants enrolling in clinical trials of Alzheimer's treatments. Alzheimer's, which gradually destroys memory and thinking skills, is characterized by changes in the brain including buildup of amyloid beta plaques and tau tangles that result in loss of neurons responsible for transmitting information.

Currently, people who might benefit from Leqembi, the new Alzheimer's drug from Eisai and Biogen (NASDAQ:BIIB), need those changes diagnosed through cognitive assessment and a cerebrospinal fluid (CSF) test, which requires an invasive lumbar puncture, or an expensive PET brain scan that may not be reimbursed by health insurers.

Even when covered, CSF and PET testing can be hard to access in some parts of the country. Researchers have been working for years on blood tests for Alzheimer's that can replicate these diagnostic tools. But there is still debate over which biomarkers, or proteins in the blood, signal the presence of amyloid and tau in the brain.

They also say more work is needed to understand the relationship of such biomarkers with race, underlying medical conditions and other