In a highly anticipated announcement, the US Food and Drug Administration last week approved the first new drug for Alzheimer’s disease in nearly two decades.

That approval was not without controversy. Both before and after the FDA’s decision, physicians and researchers expressed a wide variety of perspectives on the drug’s potential, given a limited evidence base, and multiple stops and starts in its development and approval process.

The Alzheimer’s drug, called aducanumab during development and clinical trials, will be branded and sold as Aduhelm.

“I really believe this kicks off a new era in the fight against Alzheimer’s disease,” says Stephen Salloway, professor of neurology and psychiatry at Brown University who has been closely involved with the drug’s clinical development since the beginning.

Salloway directs the Memory and Aging Program at Butler Hospital and has been researching Alzheimer’s disease for 30 years.

He was a site principal investigator at Butler for both Phase 1 and Phase 3 trials of aducanumab, co-chair of the investigative steering committee for the Phase 3 program, and has advised the drug’s manufacturer, Biogen, on safety protocols and side effect management.

Here, he explains the key takeaways from the FDA’s headline-making decision and what it means for Alzheimer’s patients and for future research of the disease: