TOKYO (Reuters) - Japanese drugmaker Eisai is developing a dementia treatment that it aims to commercialise in the U.S. by fiscal 2030, the Nikkei reported on Sunday.

The new drug targets a protein called tau, which causes symptoms of Alzheimer's disease, the newspaper reported.

Eisai already has a dementia drug on the U.S. market called Leqembi, co-developed with U.S. peer Biogen.

The companies announced on Friday that they would start Leqembi sales in China, making that country the third where the treatment is available after the U.S. and Japan.

(Reporting by Kevin Buckland; Editing by Christopher Cushing)