US health authorities on Friday approved a new Alzheimer’s drug aimed at reducing cognitive decline in patients suffering from the neurodegenerative disease, a long-awaited treatment after a previous drug with a similar mechanism failed to launch a year and a half ago, AFP and Reuters reported.

The new treatment, lecanemab, which will be marketed as Leqembi, is now recommended by the US Food and Drug Administration (FDA) for patients whose disease has not yet reached a very advanced stage.

For example, lecanemab, developed by companies Eisai Co Ltd 4523.T and Biogen Inc BIIB.O, is recommended for patients in the early stages of the disease.

Initial patient access will be limited by a number of factors, including reimbursement decisions for Medicare, the U.S. government’s insurance program for Americans age 65 and older, who make up about 90 percent of people likely to be eligible for Leqembi.

The drug is intended for patients with mild cognitive impairment or early Alzheimer’s dementia, a population that doctors believe is a small fraction of the roughly 6 million Americans currently living with the disease, which includes memory loss.

Leqembi has been approved under the FDA’s expedited review process.

Eisai officials said they also plan to provide data from a recent 1,800-patient clinical trial as the basis for a full standard review of Leqembi.

This study showed that Leqembi, given by infusion, slowed the rate of cognitive decline in patients with early Alzheimer’s disease by 27% compared to a placebo.

But the study also found serious side effects: some patients had brain hemorrhages. In addition, at least one person who received treatment died, AFP reported.

Reuters writes that nearly 13 percent of patients treated with Leqembi in the study experienced brain swelling. An autopsy of a 65-year-old patient taking lecanemab who suffered a stroke showed that emergency treatment with a standard clot-busting drug led to a fatal brain hemorrhage. At least one other patient in a later study of lecanemab died of a brain hemorrhage, raising concerns that the anticoagulants may increase the risk of dangerous brain swelling.