Blood tests for Alzheimer's may be coming to your doctor's office. Here's what to know

WASHINGTON (AP) — New blood tests could help doctors diagnose Alzheimer’s disease faster and more accurately, researchers reported Sunday – but some appear to work far better than others.

It’s tricky to tell if memory problems are caused by Alzheimer’s. That requires confirming one of the disease’s hallmark signs — buildup of a sticky protein called beta-amyloid — with a hard-to-get brain scan or uncomfortable spinal tap. Many patients instead are diagnosed based on symptoms and cognitive exams.

Labs have begun offering a variety of tests that can detect certain signs of Alzheimer's in blood. Scientists are excited by their potential but the tests aren't widely used yet because there's little data to guide doctors about which kind to order and when. The U.S. Food and Drug Administration hasn't formally approved any of them and there's little insurance coverage.

“What tests can we trust?” asked Dr. Suzanne Schindler, a neurologist at Washington University in St. Louis who’s part of a research project examining that. While some are very accurate, “other tests are not much better than a flip of a coin.”