TOKYO, Dec 22 (Reuters) - Japan's Sysmex Corp said on Thursday it had received regulatory approval in Japan for a blood test to detect amyloid beta in the brain, a characteristic of Alzheimer's disease.

The company developed the test with Japanese drugmaker Eisai Co and gained approval from regulators on Dec. 19, it said in a statement.

The test kit uses a small amount of the patient's blood to measure amyloid beta accumulation in the brain, allowing for earlier diagnosis and treatment.

Sysmex, a maker of medical equipment and clinical tests, said it was preparing for market introduction as soon as possible.

Eisai and its U.S. partner Biogen Inc are planning to seek full approval of their experimental Alzheimer's drug lecanemab in the United States, Europe and Japan next year. (Reporting by Rocky Swift Editing by Mark Potter)