Understanding how the objective neighbourhood built environment influences depressive symptoms and quality of life in Hong Kong older adults

Abstract

Depression is common amongst older adults and contributes to disability in late life, which can, in turn, lower quality of life (QoL). The neighbourhood environment is importantly related to older adults who may confine their lifespace to local areas due to age-related chronic health problems and declining physical function and mobility. Older adults with specific characteristics (e.g., living alone) are deemed to be more susceptible to their neighbourhood environment. Given the population ageing both globally and locally, corresponding health burden is expected to increase substantially. It is therefore important to identify large-scale modifiable environmental factors that can influence mental health in old age. However, previous research mainly focused on social aspects of the neighbourhood environment that tend to be less amendable compared to their built/physical counterparts. The limited studies on built environment frequently used self-report measures of neighbourhood attributes, which can be subject to reverse causality whereby individuals’ affective states affect their perception of the environment. Also, compelling evidence exists that specific neighbourhood attributes are related to physical activity (PA) associated with multiple health benefits, including reduced depressive symptoms and improved QoL. Yet, whether such PA mechanism underpins the relationships between neighbourhood environment and depressive symptoms/QoL in older adults remains unknown. In light of the above, this thesis aims to investigate the relationships between objectively-assessed aspects of the neighbourhood built environment, depressive symptoms, QoL, PA and individual-level characteristics (i.e., gender and living arrangements) in Hong Kong Chinese older adults, based on data sourced from the Active Lifestyle and the Environment in Chinese Seniors (ALECS) project. A range of neighbourhood environmental attributes were objectively quantified using geographic information systems and environmental audits, whilst depressive symptoms and QoL were measured via the intervieweradministration of validated questionnaires. Self-reported PA and sociodemographic and health-related characteristics were also included in analyses. Appropriate analytical approaches (e.g., generalised additive mixed models and joint-significance tests) were employed to estimate the dose-response relationships of interest. A number of neighbourhood attributes were identified as environmental correlates of depressive symptoms and/or QoL domains in older adults, particularly amongst those living alone, and associations were linear and/or curvilinear. Several gender-specific environment–QoL associations were also observed. PA mediated/suppressed the observed main and/or moderated associations of depressive symptoms and QoL domains with specific environmental attributes, including street intersection and entertainment densities, access to multiple destinations, street connectivity, prevalence of public transport, park attributes, and presence of litter/decay. The findings reveal the complexity of neighbourhood environment–depressive symptoms/QoL associations in older adults living in an ultra-dense metropolis, dependent on individual factors (e.g., gender and living arrangements). PA mechanism was shown to be partially responsible for these main associations and moderation effects. Environmental stressors (e.g., traffic-related noise and pollution) arising from high density areas may deter participation in PA, yielding negative effects on mental health and QoL. Engagement in activities other than PA (e.g., socialising) that are potentially affected by characteristics of the neighbourhood environment could possibly explain the observed associations. Future research is required to examine a multitude of competing pathways of environmental influences.