LOS ANGELES, CA (Catholic Online) - Specialists say the results were promising, but warned that successful drugs in laboratory test subjects often fail to work in humans.

While the cause of Alzheimer's remains unknown, one of the leading theories involves the formation of clumps of a protein called beta-amyloid. These damage and kill brain cells, leading to memory problems and the inability to think clearly.

Clearing protein plaques is a major focus of Alzheimer's research and drugs are already being tested in human clinical trials.

The role of removing beta-amyloid falls to apolipoprotein E, or ApoE for short. People have different versions of the protein and having the ApoE4 genetic variant is one of the biggest risk factors for developing the disease.

Scientists at the Case Western Reserve University in Ohio were investigating ways of boosting levels of ApoE, which in theory should reduce levels of beta-amyloid.

They tested bexarotene, which has been approved for use to treat cancers in the skin and on mice with an illness similar to Alzheimer's.
After one dose in young mice, the levels of beta-amyloid in the brain were "rapidly lowered" within six hours and a 25 percent reduction was sustained for 70 hours.

In older mice with established amyloid plaques, seven days of treatment halved the number of plaques in the brain.

Researchers found improvements in brain function after treatment, such as nest building, maze performance and remembering electrical shocks.

"This is an unprecedented finding. Previously, the best existing treatment for Alzheimer's disease in mice required several months to reduce plaque in the brain," Researchers Paige Cramer said.

The research is at a very early stage, and drugs often do not make the leap from animal experiment to human treatment.

Fellow researcher Prof Gary Landreth said the study was "particularly exciting and rewarding" and held the "potential promise of a therapy for Alzheimer's disease."

Landreth stressed that the drug had been tested in only three "mouse models" which simulate the early stages of the disease and are not Alzheimer's.

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