A Japanese research team has begun an international clinical trial to check the effectiveness and safety of a treatment for familial Alzheimer's disease.

According to recent announcements, the team of researchers from Niigata University and the University of Tokyo began the trial to test administering a combination of Alzheimer's drug lecanemab and a new drug under development.

It is the world's first trial combining lecanemab with another drug. The team hopes that the trial will lead to the development of a new remedy method.

Symptoms of familial Alzheimer's disease appear mostly in people in their 30s to 50s. Patients make up less than 1% of all Alzheimer's patients.

People inheriting a genetic abnormality responsible for familial Alzheimer's disease often show symptoms around the same age as their parents did.

An effective treatment has yet to be developed for the disease, which is believed to be caused by the accumulation of amyloid beta and tau proteins in the brain.

The clinical trial is under way in 16 countries. In Japan, four people in their 30s to 50s are participating.

While lecanemab is being administered to all participants, half of them are also given the new drug and the other half a placebo. Researchers will examine the accumulation of the proteins in the brain and the effectiveness of the treatment over four years.

"If the treatment proves effective in the clinical trial, it is expected to lead to the development of a treatment for sporadic Alzheimer's disease, which affects a large number of patients," Niigata University professor Takeshi Ikeuchi said.