WASHINGTON — Health advisers on Friday unanimously backed the full approval of a closely watched Alzheimer’s drug, a key step toward opening insurance coverage to U.S. seniors with early stages of the brain-robbing disease.

The drug, Leqembi, received conditional approval from the Food and Drug Administration in January based on early results suggesting it could slow Alzheimer’s progression by several months. The FDA now is reviewing more definitive results to decide whether the drug should receive the agency’s full endorsement.

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