Milwaukee, Wis. ? Scientists have been able to induce brain disease in mice by injecting extracts of the brains of people who died of Alzheimer’s disease, a finding that suggests that Alzheimer’s has some characteristics of prion brain disorders such as mad cow disease and chronic wasting disease.

The research also shows that under extreme laboratory circumstances, an Alzheimer’s-like disease can be transmitted.

Scientists not connected with the study said it points to important new ways to look for the causes of Alzheimer’s and potential new treatments.

“It’s fabulous work,” said Sam Gandy, an Alzheimer’s researcher and director of the Farber Institute for Neurosciences at Thomas Jefferson University. “This is the first time a brain of a human with Alzheimer’s has been used to provoke pathology in another being.”

The study by researchers in Europe and the U.S. was published Thursday in the journal Science.

The study leaves open the possibility that something in the environment, such as a toxin or even a tiny viral agent, might be involved along with a key protein in causing Alzheimer’s, said Gandy, who also is a spokesman for the Alzheimer’s Assn., which partially funded the study.

Beta-amyloid is the protein that builds up in the brains of people with Alzheimer’s disease.

All people make beta-amyloid in their brains, but in some it builds up, probably beginning in midlife, and becomes the hallmark of Alzheimer’s.

For the study, researchers used mice that were genetically engineered to produce a human form of beta-amyloid in their brains.

Within about a year after birth, these transgenic mice normally would develop clumps of beta-amyloid in their brains, much like what happens in people with Alzheimer’s disease.

However, when the mice were injected with brain extracts that contained beta-amyloid from people who had died of Alzheimer’s, the plaques appeared within a few weeks.