THE RELATIONSHIP BETWEEN DEFAULT MODE HYPERACTIVITY, DECISION MAKING, AND DEPRESSION AND ADHD

Abstract

The default mode network (DMN) is a neural network involved in many cognitive processes, one being decision making. When the DMN is not properly suppressed by the task-positive network (TPN), such as in ADHD and depression, this can lead to hyperactivity of the DMN. Decision making is also impaired in ADHD and depression, which begs the question: how does hyperactivity of the default mode network affect decision making in disorders such as depression and ADHD? This review focuses on perceptual decision making, explore-exploit decision making, and temporal decision making to answer this question. ADHD subjects displayed reduced DMN functional connectivity between the DMN and TPN, possibly due to dysmaturation of their connectivity in adolescence, which was associated with worse performance on temporal discounting tasks and was significantly correlated with delay aversion. Major depressive disorder (MDD) subjects exhibited increased risk-averse behavior and stronger functional connectivity of the posterior cingulate cortex (PCC) and precuneus lobule (PCUN), which is indicative of DMN hyperactivity. Furthermore, the medial prefrontal cortex (mPFC) plays a role in both emotional and explore exploit decision making. Overall, it was concluded that DMN hyperactivity in ADHD and depression was correlated with impaired decision making. These results could be used to improve upon treatment options for ADHD and depression.