Systemic Environmental Factors, Neural Correlates and Psychosis Vulnerability

Vargas, Teresa

doi:https://doi.org/10.21985/n2-fsjv-tb15

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Systemic Environmental Factors, Neural Correlates and Psychosis Vulnerability

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Relative to individual level exposures (such as childhood trauma, life events, and bullying exposure), contextual or systems level environmental factors have received relatively less attention in the psychology literature. While landmark epidemiological and sociological studies have uncovered key insights with regards to systems, this knowledge has not often been translated to informing clinical science. Less is known about how systemic factors could inform clinical phenomenology, and putative biological or developmental mechanisms remain largely unexplored. Further, existing studies on ecological characteristics have largely focused on adult populations, and much less is known about the interplay of systems and dynamic developmental periods of childhood, pre-adolescence, and adolescence, during which dynamic gray matter development is taking place. These efforts could be particularly informative with regards to psychotic disorders, which are highly prevalent, debilitating, heterogeneous, and neurodevelopmental. The current dissertation sought to explore systemic environmental exposures, relations to psychosis vulnerability, and gray matter morphometry. Domains of exposures were explored, including stimulation (lack of safety and high attentional demands), discrepancy (social exclusion and lack of belonging), and deprivation (SDD; lack of environmental enrichment) features. Study 1 explored how context could influence the presence or severity of suspiciousness in adolescents and young adults at clinical high risk (CHR) for psychosis, finding that greater stimulation/neighborhood crime (assessed using objective geocoding measures) related to increased suspiciousness, even after accounting for deprivation/neighborhood socioeconomic status. Result support the notion that assessing types of contextual features could aid validity and reliability of symptom assessments. Study 2 harnessed the power of a nationally representative United States dataset of children and pre-adolescents to explore systemic factors and psychotic-like experiences (PLEs). Objective self-report exposures for deprivation showed significantly stronger relations with PLEs, compared with discrepancy and stimulation exposures. Further, a factor analysis was conducted using self-report items. Five factors were defined, and four were consistent with the three hypothesized domains, and related to PLEs. Study 2 supported the notion that incorporating contextual and ecological features could inform psychopathology prevention and intervention. Finally, study 3 sought to explore systemic environmental exposure domains and hypothesized relations to neural regions. Self-report and objective environmental domains related to area/thickness in overlapping (e.g., insula, caudal anterior cingulate), and unique regions (e.g., for discrepancy, rostral anterior and isthmus cingulate, implicated in socioemotional functions; for stimulation, precuneus, critical for cue reactivity and integration of environmental cues; and for deprivation, superior frontal, integral to executive function). Results represent a necessary step toward broader work aimed at establishing mechanisms and correlates of structural disadvantage, further highlighting the relevance of going beyond aggregate models by considering types of environmental factors. Taken together, this dissertation’s work lends support to the notion that types of systemic exposures could help clarify degrees of vulnerability, as well as symptom presentation, and ultimately could inform prevention and intervention efforts at the individual and health policy level.

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