Specific Protein Form Linked to Alzheimer's Disease

Scientists may have discovered a new clue to the cause of Alzheimer's disease. A sticky protein called beta-amyloid clutters the brains of Alzheimer's victims. Researchers have been trying to determine whether the protein causes Alzheimer's or is a side effect of the memory-robbing disease. Scientists are also studying tangles of protein called tau as a potential cause.

In new research reported in the journal Nature Medicine, Harvard Medical School scientists found that rats injected with one particular form of beta-amyloid -- a two-molecule soluble form -- developed Alzheimer's. Injections of other forms of beta-amyloid -- one and three-molecule soluble forms and insoluble forms -- did not cause illness. Researchers believe this could be the reason why some people with beta-amyloid plaque in their brains do not develop Alzheimer's symptoms.

Rats injected with two-molecule soluble beta-amyloid showed impaired memory function, particularly for new behaviors. The density of their brain cells was also reduced by 47%. This is the first indication that a specific protein is related to Alzheimer's disease and spurs hope for a future cure.