WASHINGTON - The discovery of
enzymes that react abnormally in the skin of patients with Alzheimer's disease
could lead to quick, painless test for the disease, U.S. researchers said on
Monday.
It could not only quick and easy, but it would be the first accurate test for
diagnosing Alzheimer's disease, which can now only be diagnosed by careful
psychiatric assessments and by examining the brain after death.
Tapan Khan and Daniel Alkon at the Blanchette Rockefeller Neurosciences
Institute in Rockville, Maryland said their test distinguished Alzheimer's from
other brain-damaging diseases such as Parkinson's.
Writing the Proceedings of the National Academy of Sciences, they said it
might even be used to find Alzheimer's, the most common cause of dementia, early
on, when drugs may do the most good.
"When it begins, Alzheimer's disease is often difficult to distinguish from
other dementias or mild cognitive impairment," Alkon said in a statement.
"Potential treatments of Alzheimer's, however, are likely to have their
greatest efficacy before the devastating and widespread impairment of brain
function that inevitably develops after four or more years."
Alzheimer's disease is marked by inflammation, which in turn is caused by a
variety of compounds in the body.
Alzheimer's specifically stimulates a change in an enzyme called MAP Kinase
Erk 1/2, Alkon and Khan found.
They tested this on various tissue samples taken from people who had died of
known causes, including people who had died with Alzheimer's.
When they tested skin cells with bradykinin, a common inflammatory signal,
the Erk 1/2 response in Alzheimer's patients was different from that seen in
tissues taken from other people.
That included patients with dementia caused by Parkinson's disease, multiple
infarct dementia and Huntington's chorea.
More than 4.5 million people have Alzheimer's disease in the United States
alone and 12 million worldwide. There is no cure.
