The study, published in Proceedings of the National Academy of Sciences, found mice which survived infection with an H5N1 flu strain were more likely than uninfected mice to develop brain changes associated with neurological disorders. These changes included a 17 percent loss of the same neurons lost in Parkinson's disease and the accumulation of a protein in certain brain cells associated with Alzheimer's diseases.
"This avian flu strain does not directly cause Parkinson's disease, but it does make you more susceptible," study senior author Richard Smeyne, of St. Jude's Children's Research Hospital based in Memphis, Tenn., said in a statement.
"Around age 40, people start to get a decline in brain cells. Most people die before they lose enough neurons to get Parkinson's. But we believe this H5N1 infection changes the curve. It makes the brain more sensitive to another hit, possibly involving other environmental toxins."
Parkinson's and Alzheimer's diseases usually hit later in life and involve the loss of brain function crucial to movement, memory and intellectual functioning.