An experimental drug that claims to slow the progression of Alzheimer’s disease is getting mixed reviews from scientists.

Developers of the drug aducanumab made their case at an Alzheimer’s conference in San Diego in early December, two months after they reported results that suggested the drug was showing signs of being effective at high doses. It was an about-face from earlier in the year, when two studies were stopped because the drug wasn’t believed to be working.

Due to the debilitating nature of the disease, one for which there is not only no cure, but no effective treatment, patients and families are putting pressure on the U.S. Food and Drug Administration to approve any drug that might even barely offer any help.

Doctors and scientists largely agree, but they offer a warning to proceed with caution.

“I don’t see how you can conclude anything other than that another trial needs to be done,” Dr. David Knopman of the Mayo Clinic told the Associated Press.

Others are taking more from the results.

“This is an important moment for the Alzheimer’s community,” Maria Carrillo, chief science officer at the Alzheimer’s Association, said to the AP. While not offering a cure, “it may mean that they remember their loved ones a little longer.”

The drug’s goal is to remove plaques, or harmful protein clumps, from the brain. The most promising result of the studies was that it slowed the rate of mental decline by 22 percent over those who took a placebo.

But even the drug’s manufacturers warn that the initial studies left plenty of questions that need to be addressed in future studies, including dosage amount.