A surprising discovery has been made in the treatment of Alzheimer's, the brain disease that causes memory loss and other problems.

A drug used to treat women's menstrual pain made memory problems disappear in laboratory animals with Alzheimer's disease.

The researchers gave the medicine -- mefenamic acid -- to mice with Alzheimer's disease. The scientists say treatment reversed the animals' memory-loss problems.

Alzheimer's is a progressive disease. It worsens over time. It affects many parts of people's lives, including the ability to remember, think and make decisions.

The findings were published in the journal Nature Communications. David Brough of Britain's University of Manchester led the research.

This is how the experiment worked:

The scientists did experiments with mice that were engineered to develop Alzheimer's symptoms.

Like humans who get the disease, the laboratory mice developed memory problems over time.

Ten of the Alzheimer's mice were treated with mefenamic acid for one month. The drug was contained in very small pump devices placed under their skin. Ten other mice, also with memory problems, had devices placed under their skin too, but theirs did not contain medicine.

Then the animals were placed in a maze -- a complex group of connected paths. They had to learn how to move around the maze without problems.

Mike Daniels was a researcher on the study. In a Skype interview he said the mice who received the drug learned the maze easily. That was not true for the mice who did not get the medicine.

"We tried to train the mice once they had Alzheimer's Disease, and the Alzheimer's mice are un-trainable. They cannot learn that maze."

Amazing results

The researchers were excited by the results with the drug-treated mice.

"What was just amazing is, is that this drug seemed to, seemed to render the mice completely normal. It is something we have not really seen before, but there needs to be a lot more work done to really confirm whether this is, whether this is real."

How does this drug work?

Daniels says brain imaging shows a lot of harmful inflammation in the brains of Alzheimer's patients. Inflammation is a condition in which parts of your body swells, warms and often hurts.

Researchers believe mefenamic acid reduces that brain inflammation. But other drugs -- like ibuprofen -- which are also used to stop inflammation, did not help.

Jack Rivers-Auty is the study's co-author. He says it is difficult to say whether mefenamic acid would work at all stages, or levels, of Alzheimer's. The stages change from mild thinking and memory problems to the inability to communicate in any way.

He says if researchers move forward with human testing "we would definitely want to put it into people at the early stages of the disease." That way, researchers could try to slow the progress, or even stop the progress, of the disease.

The researchers say the drug is already approved by the U.S. government and is known to be safe. So, after more testing, mefenamic acid may be available quickly to treat Alzheimer's patients.

Different drug shows promise in humans

In another recent study, researchers testing a drug on humans found it slowed the progress of Alzheimer's Disease. People were given aducanumab, a drug that fights substances that build up in the brain of Alzheimer's patients.

The substances are called amyloids. They are sticky proteins that group together in the brain. Together, they form what are called amyloid plaques, and are thought to be a cause of Alzheimer's.

The researchers reported that in the brains of those given the treatment, there was an "almost complete clearance" of the amyloid plaques, according to the AFP news agency.

But researchers said that while the results are exciting, it is too early to know if this is an effective treatment for the disease. More tests are planned.

The study results were published in the journal Nature.

Alzheimer's is the most common form of a group of brain diseases causing memory loss that are collectively called "dementia."

The World Health Organization says more than 47 million people worldwide are affected by dementia. Nearly eight million new cases are diagnosed each year.

I'm Anne Ball.

Jessica Berman reported this story for VOANews. Anne Ball adapted it for Learning English. Caty Weaver was the editor.