Uncovering Spatial Patterns and Temporal Trends in the Ageing of the Tokyo Metropolis Population

Abstract

Urban populations are ageing, but the spatial and temporal distribution of the older adult population is highly heterogeneous, which has implications for resource allocation, service provision, and infrastructure needs. Based on the method proposed by Atkins & Tonts (2016), we used the interplay between changes in the number and proportion of the older adult population to identify population ageing types: accumulation (both the number and proportion of the older adult population increases); decline (both the number and the proportion of the older adult population decreases); dilution (the number of individuals in the older adult population increases while the proportion decreases); and concentration (the number of individuals in the older adult population decreases while the proportion increases). We investigated the spatial distribution and temporal trends of these types of population ageing in the Tokyo Metropolis during 2000–2015 in a 500-m grid using distance from the JR Yamanote Line and the nearest train station as geographic reference points. Accumulation and dilution occurred in east Tokyo, peaking at 10–40 km from the JR Yamanote Line and decreasing within 1 km of the nearest train station, respectively. Decline and concentration increased with distance in west Tokyo, and were more prevalent at distances of more than 40 km from the JR Yamanote Line and more than 8 km from the nearest train station. The allocation of urban resources should be optimised to meet the changing needs of the ageing population, particularly in suburbs and mountainous areas.