Scientists Intrigued by Old Drug That Reverses Signs of Alzheimer’s in Mice

The next new treatment for Alzheimer’s disease may be an already-existing drug, according to a team of researchers in Japan.

In a series of experiments, administering an oral dose of an amino acid called arginine, which is already prescribed to treat high blood pressure, was able to suppress the buildup of a protein associated with Alzheimer’s in mice, the scientists report in a new study published in the journal Neurochemistry International.

“Our study demonstrates that arginine can suppress amyloid-beta aggregation both in vitro and in vivo,” study coauthor Yoshitaka Nagai, neuroscientist at Kindai University, said in a statement about the work. “What makes this finding exciting is that arginine is already known to be clinically safe and inexpensive, making it a highly promising candidate for repositioning as a therapeutic option for Alzheimer’s disease.”

Scientists still don’t understand the underlying cause of Alzheimer’s disease, but amyloid-beta proteins figure somewhere in the question. Though they’re a part of normal brain function, they’re sticky and can clump together to form “plaques” in the brain. These plaques are considered a hallmark of Alzheimer’s, though not all patients with the disease are found to have them.

According to the researchers’ findings, the arginine can help flush these plaques and break them apart. They demonstrated this by feeding mice with amyloid-beta buildup in their brains drinking water and food infused with small doses of the drug.

Along with breaking up the buildup, they also found that the mice which were administered arginine showed improved behavior and cognitive performance, suggesting that the drug helped reverse some of the disease’s harmful effects. This was assessed by analyzing how the mice navigated an elevated Y-shaped maze, noting how far the mice traveled and how many times it entered the maze’s “open arms,” a test of a healthy mice’s natural instinct to avoid open spaces and enter enclosed ones.

Human clinical trials are needed to bear out the medical potential, but the researchers are optimistic.

“Given its excellent safety profile and low cost, arginine could be rapidly translated to clinical trials for Alzheimer’s and potentially other related disorders,” Nagai said in the statement.

Other recent studies have explored promising avenues for treating Alzheimer’s. A team of scientists in China said they were able to almost instantly reverse the disease’s progression using nanoparticles injected in their brains that cleared the plaques and led to cognitive improvements. Another team in Japan used synthetic peptides to reverse progression in early stages of the disease.

Still, amyloid-beta’s function in the brain in general remains a mystery, and so the jury’s still out on whether targeting them is a meaningful way of treating, let alone curing, the tragic disease.

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