Three decades after the presumed cause of Alzheimer′s disease was identified, a Japanese company has become the first drugmaker to prove the condition can be slowed. Eisai Co. is a Tokyo-based pharmaceutical company with a family bent and a market capitalization of about $14 billion.

The results of their Clarity-AD trial showed that the medicine, lecanemab, curbed the most common type of dementia. Eisai felt that treating the buildup of amyloid plaque in the brains of Alzheimer′s patients could slow the disease.

On Wednesday in Tokyo, chief executive Dr. Haruo Naito stated that after 30 years, lecanemab proved that the patient′s condition can be improved by removing amyloid beta. He further added that the results proved the amyloid hypothesis.