One in Seven Japanese Seniors Forecast to Suffer Dementia by 2040

A research group within the Ministry of Health, Labor, and Welfare has estimated that the number of seniors with dementia in Japan will reach 5,842,000 by 2040, when the senior population, defined as those aged 65 or older, is nearing its peak. This increase of 1.4 million compared to 2010 means that around one in seven seniors will suffer from dementia. In addition, the number of people with mild cognitive impairment (MCI), which is a preliminary stage that may develop into dementia, is expected to be 6,128,000 by 2040. Combining the expected figures for dementia and MCI shows that roughly one-third of Japanese seniors will have symptoms of cognitive decline by that year.

During the 2022 and 2023 fiscal years, the ministry research group conducted a study of residents aged 65 or older in four towns in Japan (Nakajima, Ishikawa Prefecture; Ama, Shimane Prefecture; Nakayama, Ehime Prefecture; and Hisayama, Fukuoka Prefecture), including diagnostic tests conducted by medical specialists. The data obtained from the study was used to estimate the nationwide rates of dementia and MCI. The latter was estimated for the first time.

The study shows that the older the age group, the higher the prevalence of cognitive decline, and in the future populations of older cohorts with high rates of dementia will increase. In 2050, 5,866,000 (or 15.1%) of seniors will have dementia, and 6,312,000 (or 16.2%) MCI, and by 2060 this is expected to increase to 6,451,000 (17.7%) and 6,322,000 (17.4%), respectively.

A separate study group had found that the rate of dementia in 2012 was 15%, whereas the current research identified a lower rate of 12.3% in 2022. Professor Ninomiya Toshiharu of Kyūshū University believes that the decrease in the rate of dementia may be due to a number of factors, including the reduction in the rate of smoking, improved management of lifestyle-related diseases such as hypertension and diabetes, and improvements in health awareness.

(Translated from Japanese. Banner photo © Pixta.)