On July 6, the Food and Drug Administration (FDA) fully approved the first drug shown to slow down Alzheimer’s disease. Sold under the brand name Leqembi (generic name lecanemab), this is the first time that a drug meant to slow the disease’s progression, and not only target its symptoms, has been granted full regulatory approval. 

[Related: One big reason why Alzheimer’s might be going undetected in the US.]

Leqembi is manufactured by Japanese drugmaker Eisai and the United States-based drugmaker Biogen. The drug targets beta-amyloid, a brain protein that has long been believed by scientists to be one of the underlying causes of Alzheimer’s. 

During a phase 3 clinical trial of the new drug, disease progression was slowed by 27 percent over an 18-month period in 1,795 patients with mild cognitive impairment or early-stage Alzheimer’s. The medication also reduced sticky beta-amyloid plaques that can accumulate in the brains of people with the disease.

“[This] action is the first verification that a drug targeting the underlying disease process of Alzheimer’s disease has shown clinical benefit in this devastating disease,” acting director of the Office of Neuroscience at the FDA’s Center for Drug Evaluation and Research Teresa Buracchio said in a press release. “This confirmatory study verified that it is a safe and effective treatment for patients with Alzheimer’s disease.”

The new approval means that Leqembi should be widely covered by Medicare, which primarily serves adults 65 and older. Until this approval, the federal insurance program has only covered the cost of Leqembi for patients in certain clinical trials. This expanded coverage means that an estimated one million Medicare patients are potential candidates for the treatment, and that people with Medicare who are in the early stages of Alzheimer’s could access the drug at an affordable price. Both companies have said the treatment will cost roughly $26,500 annually without insurance.

“It’s not something that’s going to stop the disease or reverse it,” Sanjeev Vaishnavi, director of clinical research at the Penn Memory Center, told NPR. “But it may slow down progression of the disease and may give people more meaningful time with their families. It’s very exciting that we’re targeting the actual pathology of the disease.”

In January, Leqembi received accelerated approval from the FDA due to its ability to remove beta-amyloid from the brain in those in early stages of the disease that affects more than 6.5 million Americans. Full or traditional approval reflects the FDA’s assessment that the drug also helps preserve thinking and memory. 

[Related: One secret to excellent memory in old age? Giant neurons.]

The Alzheimer’s Association has previously worked to accelerate the drug’s approval, and called it “an important development for people living with Alzheimer’s disease and their families.” However, some critics have mentioned the lack of diversity in the drug’s testing pool—specifically Black patients.

According to the FDA, Alzheimer’s disease is currently irreversible, progressive, and slowly destroys memory and thinking skills. Eventually, the ability to carry out simple tasks. Its specific cause is unknown, but it is generally characterized by changes in the brain. Some of these changes include the formation of amyloid beta plaques and neurofibrillary, or tau, tangles—that result in loss of neurons and their connections.