In the fight against Alzheimer's disease, scientists have been frustrated on two fronts. They know that victims' brains contain tangled clumps of a protein called beta amyloid. But they don't know whether these cause or merely are a symptom of the deadly disease. Researchers also haven't been able to reproduce the disease exactly in animals, which would enable them to test new therapies.
Now, there's progress on both fronts. In a study reported in the Dec. 12 issue of Nature, scientists at Mount Sinai Medical Center inserted the gene for the beta amyloid protein and a special genetic switch into mouse embryos. That caused the brains of the mice to make 80 times more protein than normal. Neurobiologist Gerald Higgins of the National Institute on Aging in Bethesda, Md., then examined the mice as they aged. He found that they developed all the major symptoms of Alzheimer's, including the massive nerve-cell death that is so devastating to people.
Higgins suggests that this collaborative experiment offers compelling evidence that the protein is indeed the cause of the disease. In addition, he is already planning to use the mice to test substances that could protect nerve cells from the lethal effects of the protein.