The impact pathways of environmental, social, and behavioural factors on healthy ageing for urban dwellers aged 85+: Longitudinal study of the Tokyo Oldest Old Survey on Total Health (TOOTH).

In the context of global population ageing and concentration in cities, the population aged 80 and over (80+) is growing rapidly. Japan has the fastest ageing population and longest healthy average life expectancy, while health decline becomes pronounced and care needs increase in the 85+ age group post the 'average life expectancy'. The healthy ageing of older urban community dwellers is a pressing issue in world initiatives for sustainable urbanisation. However, for the 85+ age group, less is known about how promoting/inhibiting factors and their pathways influence healthy ageing, and related longitudinal studies remain insufficient. Using data from a longitudinal cohort study conducted from 2008-2009 to 2014-2015 among independent dwellers aged 85+ in central Tokyo (men = 203, women = 232), this study analysed the impact pathways of environmental, social, and behavioural factors on health and survival to explore promoters and potential risks on healthy ageing by gender, with multi-group structural equation modelling (SEM) and Bayesian SEM. For both genders, there was a positive chained pathway starting from friends as facilitators through positive interactions between 'social participation' and 'active behaviour' to 'ageing-related health'. Additionally, their personal networks were small, suggesting that men with family-centred networks and women with non-family-centred networks require different approaches and supports. Implications of the results are discussed, and an organised social watch and support system, which becomes more important in the 'new normal' for urban dwellers aged 85+, is recommended.