Quest Diagnostics Monday launched the first direct-to-consumer blood test to detect abnormal levels of beta amyloid, a key Alzheimer's protein which can appear years before dementia symptoms arise.

The $399 test, called AD-Detect, uses the same technology as a blood test the company launched for use by doctors in early 2022.

"One of the advantages of having an amyloid test is that it lets you know, potentially years in advance of even being symptomatic, that you are at risk for Alzheimer's," said Dr. Michael Racke, Quest's medical director of neurology.

The announcement follows full U.S. regulatory approval earlier this month of Leqembi, a drug from Eisai and partner Biogen that removes amyloid from the brain and has been shown to slow the advance of Alzheimer's in early-stage patients.

A similar treatment from Eli Lilly called donanemab is under review by the U.S. Food and Drug Administration.

Prior Alzheimer's treatments have only treated symptoms but did not address the underlying disease.

Quest's consumer test is aimed at adults aged 18 and older who may have mild memory loss or a family history of Alzheimer's and want to understand their own risk for the disease, Racke said.

Users must first pay for the test on Quest's website. Quest will then arrange for an appointment with a telemedicine doctor to order it on their behalf. If the test is positive, individuals will be contacted by a doctor from an independent physician network to discuss the next steps and potentially can share the results with other physicians, the company said.

Quest's lab-developed test, created and performed in a single laboratory, has not undergone any FDA review. The agency generally does not review such tests as long as they are prescribed by a healthcare provider.