Federal regulators have approved the first new drug for Alzheimer’s disease in nearly 20 years, leaving patients waiting to see how insurers will handle the pricey new treatment.

Health care experts expect broad coverage of the drug, which was approved Monday. But what that means for patients will vary widely depending on their insurance plan. In some cases, that could mean coming up with several thousand dollars to pay for what the insurer didn’t cover.

And there’s no guarantee that every case will be covered.