Experimental Alzheimer’s Drug, Dimebon, Raises Levels of Toxic Brain Protein, Researchers Say

A promising new Alzheimer’s drug that has been proven to delay thinking disorders in people with dementia also significantly increases levels of a toxic protein in lab mice, researchers said.

The drug, Dimebon, is being developed by Medivation Inc. and Pfizer Inc. and had been raising hopes as a possible new treatment for Alzheimer’s disease, a progressive brain disorder which affects more than five million Americans and as many as 26 people worldwide.

The new research findings of a link between Dimebon and increased levels of an amyloid protein in the brain raise serious questions about how well the drug really works.

Removing clumps of a protein called beta amyloid from the brain has long been seen as a possible way to reverse Alzheimer’s disease. While the presence of the protein in the brain is not necessarily considered a cause of the mind-robbing disease, getting rid of it seemed to do the trick.

U.S. Researchers Report Results

Researchers at Mount Sinai School of Medicine in New York, who presented their new findings at an Alzheimer’s meeting in Vienna, said the results of their study showing Dimebon increased the same toxic protein which doctors most often want to reduce in hopes of curing Alzheimer’s were “unexpected” and disappointing.

Dimebon is in late-stage testing and has seemed to delay thinking problems in people with Alzheimer’s disease, even though researchers are not sure exactly why. When they tested Dimebon on laboratory mice to see what it did to amyloid proteins, they got the answer they didn’t want to hear.

Other Alzheimer’s Drugs Suffer Setbacks

The disappointing results on Dimebon are just the latest recent setback for new Alzheimer’s disease drugs under development.

Bapineuzumab, a drug being worked on by Wyeth, Johnson & Johnson, and Elan Corp. failed last year to meet its primary goals in a mid-stage trial after it caused some brain swelling when used at higher doses, according to a Reuters news report.

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