Blood test may aid foretell Alzheimer's

According to study in University of Texas, a novel blood test can detect plaque buildup in mice brains, suggesting a possible new way to predict who might get Alzheimer's disease.Researchers at the School of Medicine in St. Louis said it is unclear whether a similar blood test would work in people, but the findings in the animal studies appeared promising.

Plaque buildup ruins brain cells and is the cause of Alzheimer's. Some people have a genetic propensity to develop this plaque later in life. The St. Louis team examined 40 mice carrying a genetic mutation to develop buildup up amyloid plaque. Two types of this amyloid protein were measured in the mice's blood. Animals then were injected with an antibody -- an immune system substance that fights infection -- called m266 -- which draws amyloid protein from the brain into the blood.

Within five minutes of the m266 injection, amyloid levels increased dramatically in the blood, indicating how much amyloid protein had built up in the mouse's brain. "That's like unbelievably fast," researcher Dr. David M. Holtzman told United Press International. "We thought if you saw anything it would take days."

The mice's brains were studied 24 hours after injection to affirm whether the levels detected in the blood had accurately reflected how much amyloid protein had built up in the brain tissue. The m266 injection appeared give an accurate picture.

"If this worked the same way in humans, it has the potential to be a predictor on who might develop Alzheimer's later," Holtzman added. M266 is a mouse antibody, Holtzman cautioned, so whether a similar human antibody exists to draw this plaque from the brain into the blood in people remains untested.

It is estimated 4 million Americans have Alzheimer's disease and that figure is expected to double in coming decades as more people live longer, though Holtzman said, "I think that's a big under-estimate," because it doesn't include folks with mild dementia.

Alzheimer's is a difficult disease to detect and doctors usually are not able to diagnose it or treat symptoms until the condition has progressed into more advanced stages. There is no cure for Alzheimer's but scientists are interested in an early screening test because earlier detection could mean starting treatment before symptoms -- such as forgetfulness, disorientation and dementia -- become unbearable.

"There's a tremendous ethical question for diagnosing (early) a disease for which this is no cure," James L. Olds, a professor of neuroscience at George Mason University in Fairfax, Va., and director of the Krasnow Institute, cautioned in an interview with UPI.

He said since there is no cure and limited treatment, telling a person they have Alzheimer's when there is no cure means that person must knowingly live with it for a longer period of time -- while they still have most of their cognitive capabilities -- rather than being told when the disease has progressed to the point they are not able to fully comprehend.

That does not mean, however, a blood test would not be useful in understanding what is taking place in the brain, he added. "If we assume what's happening in the blood is happening in the brain," he said, "that's a big red flag that things aren't going well."