New Step Toward Alzheimer's Therapy

In an experiment that suggests a break-through treatment for patients with Alzheimer's disease (AD), researchers have been able for the first time to reverse the loss of memory in mice with brain degeneration. Their work was reported in the July 2005 issue of Science.

The researchers genetically engineered mice to have the human gene that produces tau and gave them a molecular switch that could be turned off when the mice were fed doxycycline. While the gene was turned on, the mice were given memory tests in a water tank with a platform just below the water's surface. Since mice do not like water, they look for the platform. In this study, normal mice remembered where the platform was and would swim toward it. However, the genetically engineered mice appeared to become forgetful and to swim randomly around, not looking for the platform. After they were given doxycycline to reverse the effects of the tau protein, they began to look for the platform. Thus, their memory appeared to be restored even though their brains continued to accumulate neurofibrillary tangles.

From this, the researchers concluded that tau is involved in the loss and gain of memory through some other mechanism than the neurofibrillary brain tangles usually given the blame. Finding this mechanism may be the key to treating Alzheimer's.

"We hypothesize that there's an abnormal tau causing the malfunction of the hippocampus, a brain structure necessary for proper formation and storage of memories,” explained lead author Karen Ashe, professor of neurology at the University of Minnesota (Twin Cities, USA).

If the forms of tau that are causing the problem are found, scientists may be able to learn how they are formed and attempt to block the process or its affects or even to remove the proteins from the brain. Dr. Ashe cautions that the results found in mice are not often copied in humans.




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