Northwestern scientists have broken new ground in Alzheimer’s research with two new studies that may help lead to a definitive test for the degenerative disease.
Chemistry Profs. Chad Mirkin and Richard Van Duyne of NU’s Institute for Nanotechnology each conducted studies with neurobiology Prof. William L. Klein, whose work has connected the presence of tiny, poisonous proteins called ADDLs to the onset of Alzheimer’s. Mirkin and Van Duyne’s labs each developed highly sensitive diagnostic tests to detect the presence of ADDLs in a patient’s spinal fluid.
The presence of Alzheimer’s currently only can be confirmed through a brain autopsy. It is a progressive and irreversible neurological disorder that usually affects older people. No cure has been found, and symptoms often include memory loss and judgement impairment.
“There is no clinical lab test for Alzheimer’s disease,” Klein said. “So what’s emerging here is a real first step towards the first diagnostic test for Alzheimer’s disease.”
In the past, amounts of ADDLs found in spinal fluid were too minute to detect. The new tests, which use nanotechnology unique to NU’s labs, overcome that obstacle.
“Now these new assays are up to a million times more sensitive than our old assays,” Klein said. “And that’s made possible by exciting breakthroughs in nanotechnology.”
The two tests — or assays — differ in some noteworthy respects.
The approach of Mirkin’s lab, known as a bio barcode assay, is approximately 100,000 times more sensitive than the test Van Duyne’s lab uses. This means the test can can detect the proteins even if they are present in very small amounts.
Van Duyne’s lab’s method, called localized surface plasmon resonance, is able to measure the size of the proteins it detects.
According to Klein, the next step in his research will be to develop the new technology into a blood test, which would have greater practical applications than the current method of testing spinal fluid.
Asked when he expected that breakthrough might be made, Klein said, “We’d like to have had that done about a month ago.”
The new tests are a big step in the direction of pinning down the cause of Alzheimer’s, Van Duyne said.
“The big advance here,” he said, “is not to know for sure whether ADDLs are a part of the disease process. We just know that it’s a marker.”
However because of the way the test is done, researchers now also can test to find other proteins that may be associated with Alzheimer’s. The tests may help root out the cause of the disease.
“There are probably five or six proteins that have been guessed to be markers,” Van Duyne said. “And the question is which one is involved. We can find that out now.”
The general nature of the tests means they can be used to diagnose other disorders and diseases as well.
“Both approaches are completely general,” Van Duyne said. “You can detect cancer, you can detect anything.”
“I don’t know a disease that we can’t attack,” he added.
According to Mirkin, his test is being used by Prof. Steve Wolinsky at NU’s Feinberg School of Medicine to detect HIV in patients’ blood plasma samples. It is currently also being evaluated for use as a test for certain signs of cancer.
Reach Jordan Weissmann at [email protected].
