A new blood test could detect Alzheimer’s disease years before symptoms appear. Researchers say it is far more accurate than earlier blood tests.

The test measures a protein called p-tau 217 in the blood. High levels signal the brain changes that lead to Alzheimer’s. It sharply reduces false positives, the biggest problem with older tests.

The study was led by Banner Health’s Dr Nicholas Ashton as part of an international research effort. It builds on 15 years of work on blood markers for the disease.

The test costs a fraction of a PET brain scan. Results come back in weeks, compared to six to 12 months for a scan. A simple blood draw could replace costly and stressful hospital tests.

Early detection matters. New Alzheimer’s drugs work best when given early, before memory loss sets in. Millions of people could benefit.

More trials are needed before the test reaches clinics. Dr Ashton cautions that a positive result is a risk factor, not a guarantee of developing Alzheimer’s. But researchers call it a turning point in the fight against dementia.