Predicting Alzheimer's before the symptoms appear

Some day we may know years before the mind starts to go that we're at risk for Alzheimer's, much as we know today that cholesterol is a marker for later heart disease.

The National Institute on Aging and the Alzheimer’s Association announced new proposed guidelines in July, The New York Times reports. There was some muttering over this by people who felt it might give the pharmaceutical industry reason to produce drugs people might nor really need -- something the organization's denied.

Today a diagnosis — based on declining memory and reasoning abilities — requires severe symptoms. But researchers agree that Alzheimer’s smolders in the brain a decade or more before memory loss or diminished ability to reason. With new criteria for early diagnosis, the stage is set for testing drugs that might prevent the disease from running its course, investigators say.

Already, some doctors are using biomarkers, like spinal fluid tests that are commercially available, against the advice of researchers. Scientists are still working on standardizing the tests — making sure that, like a test for cholesterol or prostate cancer, an Alzheimer’s biomarker test done in one lab will give the same results as one done elsewhere. The spinal fluid tests can show levels of amyloid and another Alzheimer’s protein, tau. But it is not yet known what levels of amyloid or tau in spinal fluid are abnormal. And measurements of amyloid and tau can vary as much as 30 percent from one research lab to another.

It might be a decade or more before any drugs are found to work and approved for marketing. So there is not much people can do if they go to a private doctor, have a spinal fluid test and are told they might be in the early stages of Alzheimer’s.