Researchers say they found a clue to the cause of debilitating memory loss connected with Alzheimer's disease, a science journal reported Monday.

Biochemist Eugene Roberts and researchers at the City of Hope medical center discovered that injecting fragments of a brain protein called beta-amyloid into the brains of mice cause the mammals to forget chores they have just been taught.The findings are published in the Proceedings of the National Academy of Sciences, based in Washington, D.C.

Beta-amyloid is present in protein deposits in Alzheimer's victims' brains, but it was unclear whether the protein causes the disease or if memory loss is caused by some other disease process.

"This is really the first correlation between the presence of the (protein) in the brain and the loss of memory," said Rachael Neve, molecular biologist at the University of California, Irvine.

Neve was part of a research team that discovered fragments of the beta-amyloid protein can cause degeneration of brain cells both in test tubes and in rodents.