Washington ? A new test may help scientists answer a perplexing “which came first” question about the development of Alzheimer’s disease, possibly pointing the way to earlier diagnosis or even treatment.

Brain deposits of a small protein known as amyloid beta long have been associated with Alzheimer’s. But scientists have been unable to determine whether the body begins producing too much of the protein or loses the ability to clear it away.

Now, a research team led by Dr. Randall J. Bateman at Washington University in St. Louis is poised to find that answer with a test that for the first time can monitor the protein.

An initial test of the new technique on six healthy volunteers determined that the protein is quickly produced and quickly cleared, the researchers report in today’s online issue of the journal Nature Medicine.

Indeed, it turned out that the protein, also known as Abeta, is produced faster than any other measured before, Bateman said in a statement. He is now turning to people with Alzheimer’s in an effort to determine whether increased production or decreased clearance of Abeta is a source of the disease.