New Alzheimer's tests may improve diagnosis, treatment

Kendall Powell / Special To The Washington Post /

Although my grandmother received a diagnosis of Alzheimer’s disease in her 80s, my family was never sure that’s what she had.

She certainly suffered from dementia: She was able to recall childhood memories but couldn’t remember what she had had for lunch. But dementia and Alzheimer’s are not synonymous. Back then, the only way to look for the telltale Alzheimer’s plaques — deposits of the protein fragment beta amyloid that accumulate in the spaces between nerve cells — was through an autopsy, which we didn’t do.

Over the past 15 years, researchers have developed a greater understanding of how the disease works. We now have more accurate ways of diagnosing Alzheimer’s and are moving closer to developing drugs to directly attack the disease. Much of this work is still in the early stages, but experts are growing more hopeful about dealing with the debilitating disease, which currently has no cure.

Now, for example, we no longer have to rely on autopsies to confirm the existence of Alzheimer’s plaques. In a major advance last year, the Food and Drug Administration approved a method that uses a radioactive dye, known commercially as Amyvid, to light up amyloid plaques in a PET scan.

The FDA approved Amyvid to rule out Alzheimer’s when the scan is negative and to confirm the presence of plaques when positive, but that does not necessarily indicate the disease is present. However, some doctors are using the scans to confirm the disease, which experts say is misdiagnosed up to a quarter of the time. Paul Aisen, director of the Alzheimer’s Disease Cooperative Study at University of California at San Diego, calls Amyvid an “enormous advance” because a positive scan, combined with his clinical diagnosis, means he can tell patients and their families the disease is “present, not probable.”

However, the scans are not available everywhere, cost $3,000 to $4,000 and are not covered by Medicare or other insurers.

Still, says John Morris, a neurologist at Washington University School of Medicine in St. Louis, “families want to know.” A few of his patients have paid for the test out of pocket. “They want to put a name on it, to deal with it, even if there isn’t a curative therapy for it.”