The burgeoning field of gene-by-environment (G x E) interactions has revealed fascinating biological insights, particularly in the realm of stress-, anxiety-, and depression-related disorders. In this review we present an integrated view of the study of GxE interactions in stress and anxiety disorders, including the evolution of genetic association studies from genetic epidemiology to contemporary large-scale genome-wide association studies and GxE studies. We convey the importance of consortia efforts and collaboration to gain the large sample sizes needed to move the field forward. Finally, we discuss several robust and well-reproduced GxE interactions and demonstrate how epidemiological identification of GxE interactions has naturally led to a plethora of basic research elucidating the mechanisms of high-impact genetic variants.

With a majority of humans now living in cities, strategic research is necessary to elucidate the impact of this evolutionarily unfamiliar habitat on neural functions and well-being. In this review, both rodent and human models are considered in the evaluation of the changing physical and social landscapes associated with urban dwellings. Animal models assessing increased exposure to artificial physical elements characteristic of urban settings, as well as exposure to unnatural sources of light for extended durations, are reviewed. In both cases, increased biomarkers of mental illnesses such as major depression have been observed. Additionally, applied human research emphasizing the emotional impact of environmental threats associated with urban habitats is considered. Subjects evaluated in an inner-city hospital reveal the impact of combined specific genetic vulnerabilities and heightened stress responses in the expression of posttraumatic stress disorder. Finally, algorithm-based models of cities have been developed utilizing population-level analyses to identify risk factors for psychiatric illness. Although complex, the use of multiple research approaches, as described herein, results in an enhanced understanding of urbanization and its far-reaching effects - confirming the importance of continued research directed toward the identification of putative risk factors associated with psychiatric illness in urban settings. (C) 2015 Elsevier Ltd. All rights reserved.

With a majority of humans now living in cities, strategic research is necessary to elucidate the impact of this evolutionarily unfamiliar habitat on neural functions and well-being. In this review, both rodent and human models are considered in the evaluation of the changing physical and social landscapes associated with urban dwellings. Animal models assessing increased exposure to artificial physical elements characteristic of urban settings, as well as exposure to unnatural sources of light for extended durations, are reviewed. In both cases, increased biomarkers of mental illnesses such as major depression have been observed. Additionally, applied human research emphasizing the emotional impact of environmental threats associated with urban habitats is considered. Subjects evaluated in an inner-city hospital reveal the impact of combined specific genetic vulnerabilities and heightened stress responses in the expression of posttraumatic stress disorder. Finally, algorithm-based models of cities have been developed utilizing population-level analyses to identify risk factors for psychiatric illness. Although complex, the use of multiple research approaches, as described herein, results in an enhanced understanding of urbanization and its far-reaching effects - confirming the importance of continued research directed toward the identification of putative risk factors associated with psychiatric illness in urban settings. (C) 2015 Elsevier Ltd. All rights reserved.