Anyone who’s gone through the pain of watching a loved one endure Alzheimer’s disease knows the importance of hope.

Hope that they’ll get better. Hope that a cure will soon be found to stop the degenerative disease.

While new research suggests that an old asthma drug could be given a new purpose to help protect the brain during the progression of Alzheimer’s disease, experts not associated with the study are hopeful, yet guarded.

Researchers at the Lewis Katz School of Medicine at Temple University have published research showing that, for the first time, a prescription drug currently on the market to treat asthma may help prevent some characteristic brain lesions that contribute to Alzheimer’s disease.

The condition affects almost 6 million Americans and is the sixth leading cause of death in the United States, according to the Alzheimer’s Association.

In their study published in Molecular Neurobiology, researchers say the drug zileuton — a leukotriene biosynthesis inhibitor — can slow, stop, and potentially reverse the aggressive development of tau proteins, “the second-most important lesion in the brain in patients with Alzheimer’s disease.”

Zileuton is approved by the U.S. Food and Drug Administration (FDA) by prescription to treat asthma. It’s sold in 600-milligram tablets under the brand name Zyflo.

What the study revealed

In their study, the Temple researchers administered zileuton to mice in a laboratory.

These mice were genetically engineered to have similar tau proteins in their brains as a human with Alzheimer’s.

In the trial, however, the mice were given the human version of the tau protein, a move other researchers said adds to the validity of the study.

Mice that didn’t receive the drug had degrading memories and problems understanding their physical spaces, two common traits associated with Alzheimer’s.

Mice that were given the drug over four months, on the other hand, behaved like normal mice.

Overall, the treatment decreased inflammation and tau development, and improvement in synapses in the mice’s brains.

In other words, the mice given the asthma drug had fewer symptoms typically associated with Alzheimer’s.

The drug accomplished this, the study explains, by focusing on leukotrienes, a substance found in both the lungs and brain. It’s been linked to inflammation, a common culprit in asthma and Alzheimer’s.

Dr. Domenico Praticò, the senior investigator of the study and chair of Alzheimer’s research at Temple University, said the medication was able to “rescue” mice with established Alzheimer’s disease by interfering with the development of leukotrienes.

“At the onset of dementia, leukotrienes attempt to protect nerve cells, but over the long term, they cause damage,” Praticò said in a press release. “Having discovered this, we wanted to know whether blocking leukotrienes could reverse the damage, whether we could do something to fix memory and learning impairments in mice having already abundant tau pathology.”

Apparently, to some degree, it did.

The researchers concluded their study by saying their research represents “an ideal target with viable therapeutic potential” for treating the development of harmful tau proteins in human patients.

“This is an old drug for a new disease,” Praticò said. “The research could soon be translated to the clinic, to human patients with Alzheimer’s disease.”

Reaction to the study

That’s going to be the first hurdle of many the research has to clear before doctors start prescribing variations of asthma medication to people with Alzheimer’s.

Jimmy El Hokayem, PhD, is the head of program development for Biorasi, a Miami-based company that runs clinical trials for large drug companies, including those testing potential Alzheimer’s treatments.

He said, overall, it’s best not to get excited about studies done on animals.

“Mice are not humans,” he told Healthline. “Drugs can behave very differently in humans than in mice, producing unwanted side effects or even lacking the efficacy seen in the animals.”

But, he said, the study did address treatment, not prevention, as real-world patients are most likely to get treatment long into the development of tau proteins.

Overall, El Hokayem said there were many strengths to the research and since the drug is already approved for use in humans with asthma, it could be fast-tracked through the approval process with the FDA.

“Despite the inherent limitations of animal studies, anything that raises hope for patients can be important,” he said.

Heather Snyder, PhD, the Alzheimer’s Association senior director of medical and scientific relations, said early-stage research that uncovers potential new ways to treat other dementias “is critically important,” but the obvious next step is to determine if the drug therapy will be safe and effective for humans.

“The Alzheimer’s Association is pleased to have funded earlier work by this research team and we look forward to seeing additional research into the use of leukotriene inhibitors for dementia,” Snyder told Healthline. “The drug being tested in this study is already available on the market for another condition, which means we know a good deal about it from previous studies.”