A group of Japanese experts announced Tuesday they have developed a blood test measure to detect signs of Alzheimer's disease before patients show symptoms.

The discovery by a team led by Koichi Tanaka, a Nobel laureate in chemistry and a senior fellow of Kyoto-based Shimazu Corp., and the Aichi-based National Center for Geriatrics and Gerontology, was announced in a journal published by the Japan Academy.

One of the causes of Alzheimer's disease is abnormal accumulation of the protein amyloid beta inside the brain. With the newly developed test, the team will examine how the protein builds up and how it harms a person's cognitive functions, as there are some people who accumulate the protein but do not suffer from the disease.