Comprehensive Analysis of 30-Year Health Trends Across Japan's 47 Prefectures: Extended Life Expectancy Accompanied by Longer Periods of Ill Health and Widening Regional Disparities—Dementia Becomes Leading Cause of Death, with Slowdown in Health Improvement, Increased Risk of Diabetes and Obesity, and Worsening Mental Health Also Identified

March 21, 2025

Keio University School of Medicine

Institute for Health Metrics and Evaluation (IHME), University of Washington, USA

An international collaborative research group, led by Project Professor Shuhei Nomura of the Keio University Global Research Institute (KGRI) and the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, has conducted a comprehensive analysis of the 30-year evolution of health conditions in Japan, one of the world's leading countries for longevity. Using data from the Global Burden of Disease Study (GBD) 2021 , the group meticulously evaluated trends in various health indicators for Japan and its 47 prefectures, covering 371 diseases and injuries, including COVID-19, and 88 risk factors.

This study is an unprecedented effort to analyze 30 years of health changes from 1990 to 2021 in Japan, one of the world's longest-living nations, at the prefectural level. It identifies the health challenges of a super-aged society, which Japan is experiencing ahead of the rest of the world, and scientifically presents priority issues for health, medical, and social policies, such as reducing health disparities and responding to changes in the disease structure. The findings of this research were published online in Lancet Public Health on March 21, 2025, Japan Standard Time (March 20, British time).

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