Exposure to environmental factors increases connectivity between symptom domains in the psychopathology network

Background: We investigated to what degree environmental exposure (childhood trauma, urbanicity, cannabis use, and discrimination) impacts symptom connectivity using both continuous and categorical measures of psychopathology. Methods: Outcomes were continuous symptom dimensions of self-reported psychopathology using the Self-report Symptom Checklist-90-R in 3021 participants from The Early Developmental Stages of the Psychopathology (EDSP) study and binary DSM-III-R categories of mental disorders and a binary measure of psychotic symptoms in 7076 participants from The Netherlands Mental Health Survey and Incidence Study (NEMESIS-1). For each symptom dimension in the EDSP and mental disorder in the NEMESIS-1 as the dependent variable, regression analyses were carried out including each of the remaining symptom dimensions/mental disorders and its interaction with cumulative environmental risk load (the sum score of environmental exposures) as independent variables. Results: All symptom dimensions in the EDSP and related diagnostic categories in the NEMESIS-1 were strongly associated with each other, and environmental exposures increased the degree of symptom connectivity in the networks in both cohorts. Conclusions: Our findings showing strong connectivity across symptom dimensions and related binary diagnostic constructs in two independent population cohorts provide further evidence for the conceptualization of psychopathology as a contextually sensitive network of mutually interacting symptoms.