There is a new challenge to the U.S. Food and Drug Administration’s contentious approval of a questionable Alzheimer’s drug.

Congressional investigators in Washington say the process the FDA used to approve the drug Aduhelm was “rife with irregularities.”

The FDA overruled its own scientific advisers in approving the drug, despite a lack of evidence that it met its promise of slowing patients’ cognitive decline.

A high price tag and that lack of proof, led Medicare in the U.S. to limit use of the drug.

The FDA and drug maker Biogen have issued statements defending the approval process.

Aduhelm is not approved in Canada.

In fact, earlier this year, Biogen withdrew the drug from regulatory review with Health Canada.