International Mind, Activities and Urban Places (iMAP) study: methods of a cohort study on environmental and lifestyle influences on brain and cognitive health

Abstract

IntroductionNumerous studies have found associations between characteristics of urban environments and risk factors for dementia and cognitive decline, such as physical inactivity and obesity. However, the contribution of urban environments to brain and cognitive health has been seldom examined directly. This cohort study investigates the extent to which and how a wide range of characteristics of urban environments influence brain and cognitive health via lifestyle behaviours in mid-aged and older adults in three cities across three continents.Methods and analysisParticipants aged 50–79 years and living in preselected areas stratified by walkability, air pollution and socioeconomic status are being recruited in Melbourne (Australia), Barcelona (Spain) and Hong Kong (China) (n=1800 total; 600 per site). Two assessments taken 24 months apart will capture changes in brain and cognitive health. Cognitive function is gauged with a battery of eight standardised tests. Brain health is assessed using MRI scans in a subset of participants. Information on participants’ visited locations is collected via an interactive web-based mapping application and smartphone geolocation data. Environmental characteristics of visited locations, including the built and natural environments and their by-products (e.g., air pollution), are assessed using geographical information systems, online environmental audits and self-reports. Data on travel and lifestyle behaviours (e.g., physical and social activities) and participants’ characteristics (e.g., sociodemographics) are collected using objective and/or self-report measures.Ethics and disseminationThe study has been approved by the Human Research Ethics Committee of the Australian Catholic University, the Institutional Review Board of the University of Hong Kong and the Parc de Salut Mar Clinical Research Ethics Committee of the Government of Catalonia. Results will be communicated through standard scientific channels. Methods will be made freely available via a study-dedicated website.Trial registration numberACTRN12619000817145.

From urban neighbourhood environments to cognitive health: a cross-sectional analysis of the role of physical activity and sedentary behaviours

“…Contradictory or mixed findings have also been reported with regards to the effects of the natural environment (e.g., access to green areas) [ 10 , 14 ] and air pollution [ 15 – 17 ], although the latter category of exposures tended to be more consistently negatively related to cognitive health. These discrepant findings may be in part due to unadjusted environmental confounders, which is a common issue in the published literature [ 18 ]. For example, the failure to include traffic-related air pollution, often higher in high-density neighbourhoods [ 16 , 17 ], in studies of neighbourhood environment and cognitive health may result in the underestimation of positive effects of destination accessibility on cognitive function.…”

“…Similarly, failing to account for destination accessibility may attenuate the estimated negative effects of air pollution on cognitive function [ 9 ]. A more robust assessment of the potential effects of the neighbourhood environment on cognitive health relies on the inclusion of multiple key environmental exposures and a careful consideration of their inter-relationships in models of cognitive function, as proposed in a recent ecological model of the effects of urban environments on cognitive health [ 9 , 18 ] and in line with earlier recommendations [ 19 ].…”

“…According to this model, interrelated characteristics of the urban environment are deemed to influence cognitive health indirectly by shaping travel (e.g., engagement in active vs. motorised transport) and other lifestyle behaviours (e.g., leisure-time physical activity or gardening) and, more directly, by exposing residents to potentially harmful factors (e.g., air pollution) and/or limiting their exposures to natural environments (e.g., greenness or blue spaces) that promote restauration and social contacts [ 9 , 18 , 20 ]. Adopting this ecological framework, the present study examined how interrelated aspects of the built and natural neighbourhood environment, including air pollution as a sequela of urban densification, correlate with cognitive function in mid-age and older Australians, and the extent to which these relationships are explained by physical activity and sedentary behaviours that have been previously linked [ 3 ], or are potentially linked [ 21 , 22 ], to cognitive health (Fig.…”

“…To achieve this, we examined the total cross-sectional effects of environmental attributes on cognitive function as well as the indirect (behaviour-mediated) and direct (unmediated) effects. In general, we hypothesised that neighbourhood built environment indicators of densification (i.e., population density, street intersection density and access to various destinations) would not only show potentially beneficial effects on cognitive function via transportation [ 3 , 4 , 23 ] and leisure-time activities [ 3 , 5 , 23 ], but also detrimental effects via poorer access to parks [ 7 , 10 ], higher levels of air pollutants [ 9 , 11 , 18 ] and their impacts on leisure-time activities [ 5 , 24 , 25 ] (Fig. 1 ).…”

Development of Measures of Perceived Neighborhood Environmental Attributes Influencing, and Perceived Barriers to Engagement in, Healthy Behaviors for Older Chinese Immigrants to Australia

“…In 2016, the average population density in Hong Kong was 6760 people/km 2 [ 88 ], while that in Greater Melbourne (Australia) was 472 people/km 2 [ 89 ]. When compared to Melbourne, Hong Kong is a much denser metropolis with better access to a variety of services, transportation infrastructure, indoor places for walking, and with lower levels of crime [ 32 , 90 , 91 , 92 ]. Mirroring these differences between the two cities, Hong Kong older adults had significantly higher scores on several NEWS-CS/NEHA-CIA subscales than their Melbourne counterparts including residential density (678 vs. 51 on a scale from 6 to 789), land use diversity (3.9 vs. 2.5 on a 5-point scale), street connectivity (3.9 vs. 2.8 on a 4-point scale here and thereafter), general access to services (3.9 vs. 2.9), infrastructure for walking (3.9 vs. 2.7), and transportation (3.9 vs. 2.6).…”