The Food and Drug Administration‘s call on whether to approve Biogen‘s experimental Alzheimer’s drug, aducanumab, will be the “most important decision” the federal regulator will make in 2020, Bernstein analyst Ronny Gal said Friday.

When asked if he thought the FDA would approve the drug, Gal said, “Yes.”

“[But] you’ve got to be cautious about this,” Gal, who covers the health-care industry, said on CNBC’s “Power Lunch.”

Health industry analysts say that the FDA will be under immense pressure from advocacy groups, patients and families living with the disease to approve the drug when Biogen submits it to regulators, likely in early 2020.

Biogen’s drug targets a “sticky” compound in the brain known as beta-amyloid, which is hypothesized to play a role in the devastating disease.

The Alzheimer’s Association estimates 5.8 million Americans are living with the disease. There are currently no drugs approved by the FDA that can reverse the mental decline from Alzheimer’s, which is the sixth leading cause of death in the U.S. The FDA has approved Alzheimer’s drugs aimed at helping symptoms, not actually reversing or slowing the disease itself. Approval of the drug would likely spark excitement.

However, some analysts are skeptical of whether Biogen’s drug actually works after the company’s apparent reversal on exploring FDA approval.

In March, Biogen pulled the plug on the Alzheimer’s drug after an analysis from an independent group revealed the medicine was unlikely to work. However, the company shocked investors in late October by announcing it was seeking regulatory approval for the drug after all.

To alleviate any concerns that Biogen’s results were a fluke, the FDA could ask the biotech firm to do an additional trial before considering approval, some analysts say.

“The data is flawed; there’s a lot of questions,” Gal said in the interview Friday.

Despite the skepticism, Gal expects Biogen will still triumph.

“I kind of think it will work and they will get approval,” he said.

Gal added that it appears the FDA has been more willing to approve some drugs even if it doesn’t “cross every t and dot every i.”