Scientists at the Oklahoma Medical Research Foundation in Oklahoma City have developed a vaccine they hope can slow down or even prevent Alzheimer's disease.

Researcher Jordan Tang says the results so far are "extremely exciting" and show more testing is needed.

The experimental vaccine is designed to stimulate the body's own immune system to help it fight dementia in the brain.

Researchers say human testing could begin in three to four years.

The new research appears in The Journal of the Federation of American Societies for Experimental Biology.

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Tang and his colleagues previously identified the cutting enzyme (known as memapsin 2) that creates the protein fragments believed to be the culprit behind Alzheimer’s. In the current study, they immunized mice that had been genetically engineered to develop symptoms of Alzheimer’s.

Tang’s work also has led to the creation of an experimental drug to treat Alzheimer’s disease. That drug, which works by inhibiting memapsin 2, began human clinical trials in the summer of 2007.

Tang's research is partially funded by a grant from the Alzheimer’s Association. Alzheimer's robs its victims of memory and is the seventh-leading cause of death in the United States.

The Associated Press contributed to this report