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Dynamic Urban Environmental Exposures on Depression and Suicide

Periodic Reporting for period 4 - NEEDS (Dynamic Urban Environmental Exposures on Depression and Suicide)

Reporting period: 2021-10-01 to 2022-01-31

Mental illness is a major public health problem. Recent research found that mental health, including depression and suicide mortality, are affected by aspects of people’s living environment. It comprises the built, natural, and social settings within which people live, move, and interact. The mechanisms underpinning these environment-mental health relations are poorly understood and not universally confirmed across research.

State-of-the-art research assumed that the neighbourhood people live in is the sole health influencing environmental context. The NEEDS project called this restricting assumption into question by arguing that our contemporary society is increasingly mobile, and people are exposed to multiple environmental exposures during their daily lives (e.g. at their workplace, during travel) and over the course of their lives. Such dynamic environments can, for example, trigger, reduce, or amplify the risk of suffering from a mental disorder. With the aim to disentangle the complex relationships between dynamic environmental exposures, depression, and suicide, the NEEDS project addressed this critical knowledge gap.

The NEEDS project was the first to advance our conceptual and theoretical understanding of how dynamic exposures affect people’s depression and suicide mortality. We achieved this aim by combining several methodological innovations such as tracking people’s mobility with global positioning system-enabled smartphones, population-wide register studies, and modelling from statistics and machine learning. NEEDS marked a shift in the scientific approach to assessing dynamic environmental exposures and resulted in important insights into how these exposures relate to mental health. Since depression and suicide are increasingly prevalent, knowledge about dynamic exposures is key to revealing depression and suicide aetiologies and informing the design of health-promoting interventions and the formulation of policy, resulting in healthier urban living.
The following research steps were undertaken: First, we developed a geospatial database describing the built, natural, and social environment. The database was further used to assess people’s exposures at their home addresses and during daily moving using geographic information systems. Second, we developed a questionnaire about people’s mental health, socio-demographics, activity patterns, etc. The questionnaire was sent to 45,000 respondents in the Netherlands, and approximately 11,500 people completed the survey. About 800 respondents agreed to participate in the tracking part through a smartphone app. The data allowed us to assess how environmental characteristics at home and along people’s daily paths were associated with depression symptoms. Third, we used longitudinal Dutch register data to investigate how long-term environmental exposures along people’s residential moving relate to suicide risk based on nested case-control and cohort study designs.

The NEEDS project has been successfully completed and resulted in significant outcomes based on innovative smartphone-based tracking data and large population-based register analyses in the Netherlands. The project team published numerous peer-reviewed journal papers over the last five years, with some other articles under preparation or under review. We presented the results at conferences and published special issues. We inform the public about the outcomes through news feeds, social media content, and videos on the project web page.
Two significant achievements of the project were: First, the results showed that some exposures along people’s daily paths differ from assessments based on the home location. For example, exposure to green space in the immediate environment was associated with a reduction in depressive symptoms; but the prominence of the physical neighborhood environment should not be overstated. Second, NEEDS contributed new knowledge about physical and social environmental risk factors for suicide. Our findings provided little evidence that physical neighborhood characteristics (e.g. green space, air pollution) measured cumulatively along people’s residential histories are stronger predictors of suicide mortality than cross-sectional exposures. The social and economic context within which people live may enhance and buffer the risk of suicide.

Taken together, NEEDS broke new ground by focusing on dynamic environmental exposures. NEEDS yielded critical new insights into how these exposures relate to depression and suicide risk. Further research is required to establish the utility of dynamic approaches to exposure assessment in studies on the environment and mental health.