Negative Life Events in Adolescence Predicts Reward Bias and Functional Brain Response to Monetary Reward

• In Event: Poster Session 06
  In Poster Session: PS 06 Topic - Biological Processes: Neuroscience and Genetics

Abstract

Introduction: Negative life events (NLE) experienced during adolescence are related to an increased likelihood of future psychopathology, and research suggests that altered reward system functioning might partly underlie this association. Recent studies find associations between NLE and reward behavior (Dillon et al., 2009; Boerker et al., 2014), but these studies primarily use reaction time as a measure of approach motivation, which might not capture all aspects of reward processing. In addition, recent neuroimaging studies have found that NLE is associated with altered activation in the striatum (with most studies finding hypo-activation) during monetary reward receipt in adults and, in a few studies, in middle adolescents (Novick et al., 2018). It would be important to examine associations between NLE and behavioral and neural measures of reward system functioning during early adolescence in order to capture potential changes when reward sensitivity is starting to increase. In addition, much of the research on NLE focuses on retrospective report of early childhood trauma and maltreatment and it would be useful to understand effects of a range of events on reward system function. The current study examined associations between the experience of NLE in the past year and altered reward processing, through behavioral and neuroimaging measures, in early adolescents.
Methods: 197 adolescents (age 12-14) reported on NLE over the past year on the Negative Life Events Inventory. They then completed a behavioral Delay and Probability Discounting Task. For the discounting task, Area Under the Curve (AUC) scores were calculated for each participant, with smaller AUCs indicating greater bias to immediate reward. A subset of participants (N = 79) also completed functional magnetic resonance (fMRI) scanning, during which they completed a monetary reward task (card guessing game). Two regressions were conducted to test NLE predicting delay discounting AUC scores and whole brain response to reward outcome minus neutral outcome conditions in the reward task, while controlling for age and gender.
Results: Analysis revealed that higher NLE predicted a greater bias to immediate reward on the discounting task (b = -0.015, p < 0.05). Additionally, functional whole-brain analyses showed that higher NLE predicted higher response in right temporal pole/orbitofrontal cortex (OFC) to monetary reward receipt (FLAME, voxel-based threshold of z > 2.6, cluster-based correction p < 0.05).
Discussion: Our behavioral finding extends previous work by demonstrating the relationship between adolescent NLE and reward behavior on a task-based measure of bias to immediate reward. Our neuroimaging finding of higher brain activation in right temporal pole/OFC is inconsistent with several prior findings with adolescents of hypo-activation in the striatum to reward associated with early childhood trauma. It is possible that youth who have recently experienced more moderate levels of NLE exposure show increased neural responses, but over time those wear down and youth eventually show a blunted neural response to reward. Future research could use a longitudinal design with repeated fMRI to better capture potential functional changes following NLE exposure.

Authors

• Kelsey Mauro, George Mason University
  Presenting Author

• Tara M Chaplin, George Mason University
  Non-Presenting Author

• James Thompson, George Mason University
  Non-Presenting Author