CUMULATIVE EARLY ADVERSITY AND RESTING-STATE NETWORK TOPOLOGY IN 18- AND 19-YEAR-OLDS

Abstract

It is well established that the accumulation of early adversity exposure significantly increases risk for mental health problems across the lifespan. Yet, the neural mechanisms underlying these associations are not well understood. Cumulative early adversity may influence connectivity in large-scale resting-state networks known to be crucial to mental health – namely, the salience (SAL), default mode (DMN), and central executive (CEN) networks. However, little is known about the associations between cumulative early adversity and the topology of these networks in emerging adults or whether these associations vary based on the timing of stressor exposure. Thus, the goal of this study was to use a graph theory approach to examine how cumulative early adversity exposure and the developmental timing of adversity exposure may relate to SAL, DMN, and CEN topology in emerging adults. Participants were typically developing 18- and 19-year-olds (N = 76) from socioeconomically diverse backgrounds. They completed questionnaires and a magnetic resonance imaging (MRI) session. Using a well-validated measure—the Stress and Adversity Inventory for Adults (STRAIN) (Slavich & Shields, 2018)—participants reported on whether they experienced 55 different major stressors (e.g., death of a loved one, financial difficulties, car accident, neighborhood danger), and the timing, severity, and duration of endorsed stressors. Using this data, separate scores were computed reflecting the count and severity of stressors in early childhood (0-7 years), adolescence (13-18 years), and within the past year. Resting-state functional topology was computed as the average clustering coefficient and global efficiency of nodes in the DMN, SAL, and CEN. Multiple linear regression analyses were run to examine how cumulative stressor exposure (stressor count and severity < 18 years), stressor count and severity during early childhood and adolescence, and recent stressor exposure may relate to DMN, SAL, and CEN topology (clustering and efficiency). Exposure to more severe stressors during early childhood was associated with reduced clustering of the DMN, independent of exposure during other developmental periods (β = -.24, p = .04). Additionally, both recent stressor count (β = .28, p = .02) and severity (β = .24, p = .04) predicted increased SAL clustering and trending lower efficiency. No significant associations were seen for cumulative or adolescent stressor exposure, or for network topology of the CEN. Findings from this study provide insight into neurodevelopment following early life adversity. Results suggest that the neurodevelopmental impacts of childhood adversity may depend on the timing and severity of exposure, particularly in the DMN and SAL. Focusing on emerging adults allowed for capturing the influences that early life stressors may have as the brain nears maturity. The use of the STRAIN enabled quantifying exposure to a breadth of adversities beyond those that are typically studied in this field (e.g., maltreatment, institutional deprivation), potentially producing more generalizable results. The timing and severity of early adversity are important to consider when investigating effects on neural function and implications for risk for psychopathology.