Washington, Apr 10 : Researchers at Washington University School of Medicine in St. Louis have developed a new test that can assess whether an Alzheimer''s drug could really reduce the production of amyloid beta (A-beta)- one of the possible underlying causes of Alzheimer''s disease in humans.

With the test, called stable isotope-linked kinetics (SILK), the researchers showed that an Alzheimer''s drug given to healthy volunteers reduced A-beta production

The test could speed up the development of new treatments for the disease.

In the clinical trials by Eli Lilly and Company, the scientists are studying the drug candidate, LY450139, which is also known as semagacestat.

Ongoing clinical trials are studying the effect that semagacestat may have on cognitive function and biochemical and brain imaging biomarkers in patients with Alzheimer''s disease.

The researchers said that they wanted to see if SILK could detect the drug''s impact on A-beta synthesis in healthy volunteers.

"Bringing an Alzheimer''s disease drug into clinical trials from tests in animal models has always been challenging. We haven''t had a way to quickly and accurately assess a drug''s effects, and that meant there always had to be some degree of educated guesswork when it came to setting the optimal dosage for humans. SILK may help to eliminate much of that guesswork," said study director Randall Bateman.

The researchers are currently using SILK to know if increased A-beta production, reduced clearance or a combination of the two lead to the A-beta buildup in the brain- a process believed to trigger Alzheimer''s disease.

Until SILK, there has not been a way to directly measure the production or clearance of A-beta.

Scientists have assessed the efficacy of potential new Alzheimer''s drug candidates by monitoring the cognitive functions of patients with the disease for extended periods of time, which require large, lengthy and expensive studies.

In the new study, the scientists reported a dose-dependent drop in A-beta production, and measured an 84 percent reduction in A-beta production with the highest study drug dose.

The SILK procedure takes 36 hours, but provides scientists a more detailed assessment of amyloid beta production and clearance levels than they can obtain through conventional methods.

"You could use a spinal tap to look directly at the amount of A-beta present in the cerebrospinal fluid, but we''ve shown that natural processes cause A-beta levels to change dynamically. Such changes make it more difficult to assess the effects of a drug in that fashion," said Bateman.

The results have been published in Annals of Neurology. (ANI)