Aging in Southeast Asia and Japan: Challenges and opportunities.

Trends in life expectancy and fertility in Southeast Asia reflect the region's vulnerability to conflicts, natural disasters, infectious diseases and other crises. Southeast Asia is characterized by significant diversity, not only in its natural environment, history, religions, economic situations and political systems, but also in its challenges and healthcare systems, which include traditional medicine and local healing practices. Despite these differences, common issues are shared across the region, such as an aging population, the need for universal access to safe and secure healthcare, and the pursuit of peace and environmental harmony. Currently, Japan's aging population is more pronounced than in Southeast Asia, with a notable prevalence of older adults with chronic diseases, including dementia and living alone. However, if current demographic trends continue, most Southeast Asian nations might face similar challenges in the future. This article focuses on the 90th percentile age over time and advocates the importance of considering the relative position of age in society, rather than simply focusing on age alone. Additionally, it is recognized that individuals of the same chronological age can show significant variation in health, shaped by their life circumstances and lifestyles. As Japan leads in addressing aging-related issues, it plays a critical role in sharing its experiences. Because the health status of certain age groups in society varies from region to region and era to era, depending on the environment and culture, measures should be adapted to the realities of each society, with the cooperation of the international community to address shared challenges. Geriatr Gerontol Int 2025; ••: ••-••.