New drug holds promise for Alzheimer's patients

London, July 30 : Alzheimer's patients in the early stage of the disease showed improved brain function after the administration of a new drug, called PBT2, which reduces a key protein associated with the disease in the spinal fluid, in a new study.

PBT2 works against the production and build-up of a protein called amyloid-beta characterised by the disease that can build up into a 'plaque'.

The protein is also believed to be toxic to brain cells and to prevent them from functioning properly.

In a randomised, double-blind clinical trial led by a researcher from Imperial College London, 78 participants with early stage Alzheimer's disease took either 50mg or 250mg doses of the drug PBT2, or a placebo, over a 12 week period.

It was found that both doses of PBT2 capsules safe and well tolerated during the course of the study.

The researchers then put the participants through tests to examine their cognitive function. This was done before the treatment began and also at the end of the 12-week period.

In two such tests of executive function, which involves the ability to organise information, sequence events and plan, the subjects on a 250mg dose of PBT2 showed a significant improvement over the placebo group.

It was also measured how the levels of amyloid-beta in spinal fluid changed during the course of the trial. Levels of amyloid-beta 42 in the cerebrospinal fluid of those on the 250mg dose of PBT2 were found to be reduced by approximately 13 percent in comparison to placebo at the end of the 12-week period.

Metals zinc and copper are needed by amyloid-beta to accumulate in the brain and these two metals become abnormally distributed in the brains of people having Alzheimer's disease.

PBT2 works by interrupting the interaction between the metal ions and amyloid-beta, and returns levels of zinc and copper in the brain to normal levels.

The cognitive tests included a test known as Trail Making Part B and a Category Fluency Test, in which those in the 250mg group showed a better performance than that of the placebo group.

While memory loss is one of the biggest problem associated with Alzheimer's disease, the executive cognitive functions examined by these two tests typically begin to get worse in the early stages of the disease, though are sometimes less obvious than memory symptoms.

The scientists could not find any significant differences in participants' scores on tests assessing their memory function in the new study, but they believe that this may be due to the deterioration of memory function at a slower rate than the executive functions at this stage of illness, making changes harder to detect in a short study.

"The results of our trial are very encouraging, although it was a relatively small study, which took place over a short period of time. Our findings certainly engender much optimism that this drug may have a significant effect on the underlying pathology of Alzheimer's, with a tangible clinical benefit for patients," the Lancet quoted Dr Craig Ritchie, from the Division of Neurosciences and Mental Health at Imperial College London, who led the study, as saying.

The study was published in the journal Lancet Neurology and presented at the 2008 Alzheimer's Association International Conference on Alzheimer's Disease.

ANI