FAQ: How Close Are We to a True Alzheimer's Disease Diagnostic Test?

1 answer | Last updated: Sep 24, 2016
A fellow caregiver asked...

How close are we to a true Alzheimer's disease diagnostic test?

Expert Answers

Dr. Leslie Kernisan is a senior medical editor at Caring.com and a clinical instructor in the University of California, San Francisco, Division of Geriatrics. She also provides housecalls and geriatric consultations in San Francisco.

We're getting close to a true Alzheimer's disease diagnostic test, although it's difficult to say when something definitive will be available on a mass scale. You should realize that these tests may not be able to answer the questions people often have when they're asking about an Alzheimer's diagnosis.

Here's what I mean: It's true that new tests have been developed that identify Alzheimer's "biomarkers", special types of protein in the bloodstream, spinal fluid, or brain that correspond to having Alzheimer's disease. (They're still being refined and are mostly used for research purposes at this point.) Scientists have discovered that biomarkers appear in the body years before any symptoms, such as memory loss, become noticeable. (This is known as "preclinical" Alzheimer's, as opposed to clinical Alzheimer's, which means a person has dementia symptoms that are caused by Alzheimer's disease.)

If you have no memory symptoms now but wonder if you're likely to develop symptoms due to Alzheimer's in the next several years, then yes, these new tests may soon be able to answer that question. Experts currently estimate that Alzheimer's biomarkers are present for at least ten years before clinical symptoms become obvious.

Experts still don't know, however, how to predict when symptoms will develop in a person who is positive for Alzheimer's biomarkers, or how fast the dementia will progress once it's apparent.

For those people who are currently having memory problems or other dementia symptoms, even if Alzheimer's biomarker tests are positive, additional tests will always be necessary to rule out other causes. It's common for people to have both Alzheimer's and another problem that simultaneously affect their thinking skills.

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