A simple skin test that would allow detection of Alzheimer's disease in its earliest stages is working its way to reality. The work is based on the hypothesis that Alzheimer's disease doesn't just affect the brain, but affects the body systemically," said Dr. Daniel L. Alkon, a lead author of a report on the test.
How It Works
The test zeroes in on two forms of an enzyme involved in the degradation of amyloid, the protein that accumulates in the brain of someone with Alzheimer's, said Alkon, scientific director of the Blanchette Rockefeller Neurosciences Institute at the West Virginia University Health Sciences Center.
The presence of Alzheimer's disease is indicated by a steep imbalance in the ratio of the two forms of the enzyme, MAP kinase Erk, in skin cells that are exposed to bradykinin, an inflammation-related molecule, Alkon said. That imbalance is not seen in cells of people without dementia or those with other forms of dementia, he said.
The test produced good results when run on 60 tissue samples: 30 from a tissue bank, 30 from autopsy samples of people diagnosed with Alzheimer's disease, Alkon said.
"We have seen a correlation with the duration of the discasc," he said. "The earlier it is done in the course of the disease, the larger is the abnormality."
An as-yet unpublished study of the test done on 100 people showed equally good results, Alkon said. "We are ready to expand this to thousands," he added.
Such expanded testing is essential, said Dr. Sam Gandy, director of Thomas Jefferson University's Farber Institute for Neurosciences and chair of the Alzheimer's Association Medical and Scientific Advisory Council.
Technically, it looks perfectly sound, Gandy said of the published paper. But certainly nothing in science is accepted until it is replicated.
Having a test for early detection of Alzheimer's disease would be extremely valuable, both Alkon and Gandy said. "All the newest medications in clinical trials are aimed at the earliest stage of the disease," Gandy said.
"Drugs now are being tested on the basis of clinical diagnosis," Alkon said. "There is a major need for an early biomarker."