July 21, 2011

Scientists Are One Step Closer To Blood Test For Alzheimer’s

An experimental procedure using a blood test to screen people for early signs of Alzheimer's was able to accurately detect the proteins, which begin to build up in the brain a decade or more before they cause memory and thinking problems.

The blood test developed by scientists at Australia's national science agency, CSIRO, is the first to be validated against brain scans and other accepted diagnostic tests with good accuracy, according to results reported at the Alzheimer's Association International Conference in France on Wednesday.

Alzheimer's, the most common form of dementia, affects more than 5.4 million Americans and 35 million people worldwide, reports USA Today.

With no cure, drugs only relieve symptoms temporarily.

Early detection allows patients and their loved ones to prepare for the effects of the disease; and by ruling it out, a more treatable diagnosis such as sleep problems could be reached.

Brain scans can be used to find signs of Alzheimer's ten or more years before any symptoms occur by detecting sticky clumps of a protein called beta amyloid, but this method is too expensive and impractical for routine screening.

More simple ways are needed to screen people for the disease.

The Australian study involved a long-running study of more than 1,100 patients, with some of them healthy and others impaired.

Blood samples from 273 participants were used to identify nine hormones and proteins that seemed most predictive of amyloid levels in the brain, which had a cutoff level to determine what was considered high levels.

Samantha Burnham of CSIRO told the Associated Press (AP): "The belief is that people above that point will go on to get Alzheimer's disease, and the lag is about 8 to 10 years."

The nine-marker blood test used on these same patients resulted in separating healthy people from those with mild cognitive impairment or Alzheimer's, and was verified by their brain scans.

Results from the study accurately identified 83% of people with high amyloid levels and correctly ruled out about 85% of people without the condition.

"That's pretty high," Maria Carrillo, senior director of medical and scientific relations for the Alzheimer's Association, told the AP.

In addition, Carrillo says that the Australian researchers validated the test's accuracy in two additional groups: the Australian study of the other 817 patients and the big U.S. study that focused on finding novel Alzheimer's disease biomarkers which involved of 74 people.

Burnham says that the blood test performed well in both of those situations.

Currently CSIRO has a patent on the blood test and is seeking major companies about commercially producing it, reports the AP.

Further validation of the test is necessary to ensure it can be standardized to give reliable results regardless of which doctor or lab uses it.


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