Abstract
BackgroundThis study aimed to make future projections of the nationwide prevalence of dementia in Japan using the prevalence of dementia from the Toyama Dementia Survey and population projections.MethodsWe performed linear regression analysis using the prevalence of dementia by sex and age in 1985, 1990, 1996, 2001, and 2014 from the Toyama Dementia Survey to calculate the estimated future prevalence by sex and age. The estimated prevalence was then multiplied by the estimated future population of people aged 65 years and older by sex and age in each of the 47 prefectures from 2020 to 2045 and added together to calculate the total number of people with dementia. The estimated future prevalence of dementia was calculated by dividing the calculated number of people with dementia by the estimated future population of people aged 65 years and older in each of the 47 prefectures. In addition, the estimated future prevalence of dementia in each of the 47 prefectures from 2020 to 2045 was presented on a map of Japan and grayscale-coded in four levels.ResultsIn 2020, the estimated future prevalence of dementia did not exceed 20% in any prefecture, but in 2025, five prefectures, mainly rural prefectures, had projected rates exceeding 20%. In 2030, the prevalence rate is projected to exceed 20% nationwide, and by 2035, the rate will exceed 25% in 42 prefectures. In 2045, all prefectures excluding Tokyo are projected to have a dementia prevalence rate exceeding 25%, and the rate will exceed 30% in 12 of 47 prefectures.ConclusionsOver the next 25 years, the prevalence of dementia in people older than 65 years is projected to exceed 25% nationwide, including metropolitan areas.
Highlights
This study aimed to make future projections of the nationwide prevalence of dementia in Japan using the prevalence of dementia from the Toyama Dementia Survey and population projections
If we assume that the prevalence rate in the 2014 survey remains constant, one in every 5.4 people aged 65 and older will have dementia, which is a large difference of approximately 10% from the prevalence rate if it grows linearly to 2045
To prevent the gap from widening, we must implement preventive measures to delay the onset of dementia as much as possible to slow the acceleration of its prevalence
Summary
This study aimed to make future projections of the nationwide prevalence of dementia in Japan using the prevalence of dementia from the Toyama Dementia Survey and population projections. When we examine the problem of the increased prevalence of dementia in Japan based on data from Toyama Prefecture, in which the aging rate is slightly higher than the national average, we can predict that the same situation in Toyama Prefecture will eventually occur throughout the country. Visualizing this reality may provide an opportunity to consider countermeasures. There are no studies that have predicted future projections in the prevalence of dementia in Japan by prefecture using a highly accurate prediction model
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