The impact of urbanization on mood disorders: an update of recent evidence.

Mood disorders are highly prevalent and represent a leading cause of global disability. Urbanization holds great public health implications spanning various environmental, lifestyle behavioural, economic and social domains. Underlying risk factors for mood disorders are heterogeneous but the psychiatric literature has extended beyond individual-level risk, to account for population-level environment and social-related precursors to mental ill health. This review summarizes recent studies published since 2017 examining the impact of urbanization and associated environmental, social and lifestyle risks for mood disorders, specifically depression. All identified studies examined depression or subclinical mood-related symptomatology. Recent evidence suggests individuals residing in urban areas experience increased risk of depression. Mechanistic pathways include increased exposure to noise, light and air pollution, poor quality housing, reduced diet quality, physical inactivity, economic strain and diminished social networks. The role of the gut microbiome in the development of mood disorders represents a novel research domain expected to hold potential for the psychiatric and environmental field. Further research is needed to extrapolate the relationship between increased sedentary lifestyles and technology use and depression in urban societies. Recent evidence highlights the complexity and reciprocity of underlying driving factors in the relationship between urbanization and mood disorders. Future epidemiological research should continue to untangle such complexity. There was a dearth of evidence relating to urbanization and mood disorders other than depression. Future research should identify the unique experiences of vulnerable subgroups who experience disproportionate increased risk of adverse health experiences associated with urbanization.