New Tests Could Predict Alzheimer's
Before Symptoms Appear, Tests Promise to Detect Alzheimer's Disease
Alzheimer's Blood Test?
Obviously, an Alzheimer's screening test that requires a spinal tap will be of only limited use. While Hampel and colleagues work on developing a BACE1 blood test, a very different approach is making surprising progress.
Many of the body's cells go through continuous cycles of division, replication, and death. Normal brain cells do not. But in Alzheimer's disease, they often do.
"Some people propose that the nerve cells in the brain are trying to divide and can't, so they die," Gandy says.
Thomas Arendt, director of the Paul Flechsig Institute at the University of Leipzig, Germany, reasoned that if brain cells try to undergo abnormal cell division, maybe other cells are doing it, too.
Under normal conditions, white blood cells aren't supposed to enter the cell cycle. So Arendt and colleagues looked for CD-69 -- a protein involved in white-blood-cell growth -- in the blood of patients with Alzheimer's and Parkinson's diseases.
The CD-69 test, now licensed to the U.S. firm GW Medical, was more than 90% effective in identifying Alzheimer's patients. A larger trial is now under way; results should be available later this year.
Amyloid Goes Up, Not Down
Beta-amyloid 42 is the type of amyloid most likely to clump together and form plaques.
In earlier studies, Anne M. Fagan, PhD, of Washington University, St. Louis, and colleagues found people with unusually low levels of this sticky protein in the spinal fluid have unusually high levels of amyloid in the brain.
In a new study with 132 patients with ages ranging from 45 to 88 -- including some with mild dementia -- Fagan's team found that 97% of people with amyloid plaques forming in their brains had low levels of beta-amyloid 42 in their spinal fluid.
"A decline in beta-amyloid 42 may effectively identify non-demented individuals who are in the preclinical stage of Alzheimer's," Fagan says in a news release.