Painkillers routinely used by millions of Americans may dissolve abnormal plaque deposits in the brain linked to Alzheimer's disease, a study suggests.

The test-tube study, published in Neuroscience, adds new evidence to the theory that nonsteroidal anti-inflammatory drugs such as ibuprofen and aspirin may prevent this brain disease.

Previous studies suggested that anti-inflammatory drugs protected people from developing Alzheimer's. But those studies just showed a statistical link between such protection and the drugs.

Researcher Jorge Barrio's team at the University of California - Los Angeles looked directly at how such drugs interact with Alzheimer's plaque, abnormal clumps in the brain thought to cause the symptoms of the disease.

The team mixed a chemical marker that highlights plaque with diseased human brain tissue. They then added naproxen or ibuprofen.

The researchers found the drugs melted away some of the plaque. That finding suggests that people who take such drugs regularly may get some protection against Alzheimer's, Barrio says.

Still, Bill Thies of the Alzheimer's Association in Chicago cautions that the findings need to be confirmed with human studies.

The UCLA team plans to give the same drugs to people with early-stage Alzheimer's.

Until then, David Knopman, a neurologist at the Mayo Clinic in Rochester, Minn., warns against popping these drugs in hopes of staving off dementia. These drugs can increase the risk of stomach bleeding.

Kathleen Fackelmann