The Biogen/Eisai drug Aduhelm was the first Alzheimer's treatment to win approval in nearly 20 years, but the Food and Drug Administration's (FDA) controversial use of the accelerated approval process - which authorizes drugs for severe conditions without strong proof of a benefit to patients - has come under heavy fire.

Japanese drugmaker Eisai Co on Monday began its application process for its experimental drug for early Alzheimer's disease using an accelerated approval pathway, the same path that helped Eisai's development partner Biogen Inc win U.S. approval of its medication in June.

The Biogen/Eisai drug Aduhelm was the first Alzheimer's treatment to win approval in nearly 20 years, but the Food and Drug Administration's (FDA) controversial use of the accelerated approval process - which authorizes drugs for severe conditions without strong proof of a benefit to patients - has come under heavy fire.