Effect of Neighborhood Socioeconomic Disadvantage on Brain Functional Connectivity and Structural Properties in Trauma-Exposed Adults

Abstract

Though there has been substantial progress towards understanding brain-behavior relationships and characterizing the neurobiology of psychiatric disorders, research has not translated as expected into novel prevention and treatment of mental health conditions. One limitation may be the emphasis on individual-level variables (e.g., income) and omission of relevant area-level factors (e.g., neighborhood socioeconomic disadvantage). Recently, attention has been directed towards identifying the biological mechanisms by which neighborhoods impact mental health. The chronic stress associated with living in a disadvantaged neighborhood promotes a cascade of maladaptive events, which in turn impact brain structure and functioning. The processes affected by chronic neighborhood stressors are likewise induced when an individual experiences an acute trauma. This provides a basis for the psychological consequences of trauma, such as post-traumatic stress disorder, to be worsened or maintained by an individual’s neighborhood. More explicitly, where an individual lives may be intrinsically related to their recovery after a trauma. In a sample of over two hundred traumatically injured participants, these projects sought to identify associations between neighborhood disadvantage and brain structure and function. Each project’s analysis included a risk-resilience model, exploring interactions between socioeconomic variables and resilience factors. In the first project, I demonstrated Area Deprivation Index (ADI) rankings, a measure of neighborhood socioeconomic disadvantage, were significantly related to white matter tract integrity. Ethnoracially (ethnically/racially) minoritized individuals disproportionately reside in disadvantaged neighborhoods, and a culturally relevant resilience factor, racial-ethnic identity, buffered against the effects of ADI. In the second project, I investigated the effects of ADI on resting-state functional connectivity and structural volume of a region subserving emotion regulation processes, the anterior cingulate cortex (ACC). Using a seed-to-voxel analysis, I demonstrated lower income, but not ADI, was significantly associated with greater connectivity between the ACC and visual regions. In the final neuroethics project, I highlighted the necessity of research on area-level factors, the ethical implications of discoveries on neighborhood-mental health pathways, and the importance of devising informed policies. Ultimately, this dissertation provides additional support that sociopolitical factors represent important “missing pieces” of neuroscience research and that studies on these factors are essential in the path towards health equity.