The number of people aged 65 or older with dementia in Japan is estimated to have reached 4.62 million in 2012, accounting for about 15 percent of the total elderly population, a health ministry survey showed Saturday.
A study group of the Health, Labor and Welfare Ministry also estimated that another 4 million elderly people in Japan suffered from mild cognitive impairment, which could evolve into dementia, in 2012, up from 3.8 million in 2010, based on a research conducted between fiscal 2009 and 2012 across Japan.
When the estimated numbers of the elderly with dementia and mild cognitive impairment are put together, the combined figure suggests one in four people aged 65 or older in Japan suffer from these symptoms.
Takashi Asada, a University of Tsukuba professor specialized in dementia, and other members of the study group collected data on 5,386 senior citizens in eight municipalities across Japan by interviewing them and their families for diagnosis.
As a result of the research, the researchers projected that 15 percent of the overall population aged 65 or older in Japan -- or 4.62 million of the 30.79 million people in that age bracket in 2012 -- have developed dementia.
As of 2010, the number of people aged 65 or older with dementia in Japan was estimated at 4.39 million, of whom 2.7 million lived at home -- including about 430,000 who lived alone.
By age, the percentage with dementia among people aged 74 or younger stood at 10 percent or lower, but the ratio surpassed 40 percent among people aged 85 or older. In most age groups, more women developed dementia than men.
The health ministry had estimated last year that the number of elderly people with dementia in Japan reached 2.8 million in 2010 and 3.05 million in 2012, based on data collected on those in need of state-backed nursing care services.
The latest projections far exceed those estimates, underlining that many senior citizens with dementia do not use services provided under the public nursing care insurance scheme.