Tuesday, December 12, 2006

Possible early detection for Alzheimer’s??

Researchers at New York’s Weill Cornell Medical College found discovered certain biomarkers (a substance whose detection in our bodies indicates a particular disease state (for example, the presence of an antibody may indicate an infection)) that might seem to herald a new early test for Alzheimer’s (much before the actual onset of this devastating disease).

Researchers at Cornell seem to have found out a set of 23 proteins in the cerebrospinal fluid that seem to be an indicator for the onset of Alzheimer’s.

"Scientists believe that Alzheimer’s begins its insidious brain attack years, even decades, before forgetfulness appears — and if so, there should be evidence of those changes in the spinal fluid"

"Using a technology called proteomics, they simultaneously examined 2,000 proteins found in the spinal fluid of 34 people who died with autopsy-proven Alzheimer’s, comparing it to the spinal fluid of 34 non-demented people.
What emerged were 23 proteins, many that by themselves had never been linked to Alzheimer’s but that together formed a fingerprint of the disease."

All the patient will be required to undergo will be a spinal tap and they could be diagnosed as to whether they are at the risk of contracting Alzheimer’s later in life.
Of course a lot of this research will need to be conclusively proven, but I think that this is a quite a start for us and has a lot of potential...

"There is no single, comprehensive diagnostic test for Alzheimer's disease. Instead, doctors rule out other conditions through a process of elimination. They usually conduct physical, psychological and neurological exams and take a thorough medical history. Diagnosis is about 90 percent accurate, but the only way to confirm it is through autopsy."

"There is no medical treatment currently available to cure or stop the progression of Alzheimer's disease. There are currently five FDA-approved Alzheimer's drugs – Namenda, Cognex, Aricept, Exelon and Reminyl -- that may temporarily relieve some symptoms of the disease. Several other drugs are in development."


Birgit Zipser said...

So far, I have only read about these supposed biomarkers in an article in the Wall Street Journal. One of the papers discussed reported on elevated levels of beta amyloid peptide and hyperphosphorylated tau. I was under the impression that those peptides had been looked for in spinal fluid for several years and that, previously, no significant differences with respect to controls had been found. Please correct me if I am wrong. I know that a lot of money is being thrown into the direction of biomarkers. Perhaps some of those papers just reflect that people have to publish something for the money they have gotten?

Sunil said...

Thank you, Birgit for coming here..
Prediction of future pathology and early pre-symptomatic differential diagnosis is definitely important for an elusive illness like Alzheimer’s Disease (AD). In this regard, I definitely agree that amyloid-beta, tau, and phospho-tau are the front running biomarkers as far as AD detection is concerned, but nobody has conclusively said that the indication of the above proteins conclusively heralds an onset of AD. Hopefully research by Prof. Kelvin Lee et. al. at the Cornell School should tell us that as soon as you identify the biomarker cohort of 23 proteins, the patient definitely has AD. To my knowledge no other research has focused on it with this level of precision (but of course, that would be my ignorance speaking also).
The original paper is in published in the Dec issue of the Annals of Neurology under the title "Cerebrospinal fluid proteomic biomarkers for Alzheimer's disease".

Of course, any AD biomarker needs to fulfill the following minimum criteria (I do not claim originality for this list – got it from http://www.proteome.co.uk/pages/news/5/AD%20Presentation_Siena%202006.pdf):
-Detect a fundamental feature of neuropathology
-Validated in neuropathologically confirmed cases
-Sensitivity >80 % vs. controls
-Specificity >80 % vs. other dementias
-Reliable, reproducible & inexpensive
-Noninvasive & simple to perform
-Confirmed by at least two independent studies
-Capture the beneficial effect of disease-modifying therapy

And the people at Cornell have a ways to go before fortifying on their findings… Definitely a start.

Patryk said...

One promising detection approach that I recently heard about is the use of Pittsburgh Compound B (also known as PIB). Apparently, it crosses the blood-brain barrier, binds to the plaques that appear in Alzheimer's Disease, and can be readily detected with PET.

Sunil said...

The pathological aggregation of the β amyloid peptide into fibrillary senile plaques and the hyperphosphorylation of tau protein into neurofibrillary tangles (NFTs) play central roles in the pathogenesis of Alzheimer’s disease (AD). Pittsburgh Compound B (also known as PIB) is known to bind to fibrillary plaques and not to neurofibrillary tangles. This is the one limitation of PIB. Researchers in UCLA have announced that a PET based imaging technique using Fluorine-18 labeled short-lived radio-tracer molecule called FDDNP (http://mtbeurope.info/news/2007/701001.htm) detects both tangles and plaques on PETs.