There is increasing focus on changes in reward sensitivity that take place across adolescence; in particular, puberty appears to be a time characterized by increased sensitivity to rewards. At the same time, puberty is a time characterized by a significant increase in depressive symptoms, and depression is characterized by reductions in sensitivity to rewards. The current project examines reward sensitivity as a latent trait, capitalizing on a combination of EEG, functional neuroimaging (fMRI), behavioral, and self-report measures. Along the same lines, we consider multiple assessments of depressive symptoms (e.g., parent and child reports) so that depressive symptoms can also be modeled as a latent trait. The current proposal examines both reward sensitivity and depression in a large (N=300) sample of girls, ranging from 9 to 14 years of age; moreover, this sample will be examined two years after the initial visit, so that both cross-sectional and longitudinal relationships can be examined. In our pilot data, we have focused extensively on the feedback-related negativity (FRN), an electrocortical response observed at the scalp as an apparent negativity approximately 300 ms following feedback indicating monetary loss compared to gain. Our work suggests that the neural differentiation between gains and losses is being driven by a reward-related positive potential that is generated in the ventral striatum-part of the basal ganglia that has been implicated in reward-related neural circuits. We have found that the FRN relates to fMRI-based measures of striatal response to rewards, as well as behavioral metrics of reward sensitivity. Moreover, we have found that the FRN is reduced in both adults and adolescents who are more depressed-and have recently found that reduced reward-related brain activity can predict changes in depressive symptoms over the course of two years among adolescents. The current proposal extends this work into a much larger and longitudinal sample, and incorporates multiple measures of reward sensitivity, depressive symptoms, and puberty. We will assess: a) the relationship between multiple measures of reward sensitivity and depressive symptoms in a large sample that spans adolescence at two time points, separated by 2 years (Aim 1); b) normative developmental increases in both reward sensitivity and depressive symptoms, especially as a function of pubertal stage (Aim 2); c) prospective relations between reward sensitivity and depressive symptoms over time, and whether reward sensitivity at the first assessment can predict changes in depression two years later (Aim 3); finally, if pubertal changes predicts a stronger link between reward sensitivity and later depressive symptoms (Aim 3). A number of secondary aims are also evaluated (e.g., specificity to depressive symptoms and not anxious symptoms; utility of salivary testosterone as a marker of pubertal stage; role of stressful life events). The present study will contribute to the literature on the developmental neurobiology of reward, as well as the neurobiological changes related to individual differences in depression and risk for depression across adolescence.
We examine the role of pubertal stage and change on reward sensitivity (RS; measured using behavioral, ERP, fMRI, and self-report methods) and depressive symptoms among 300 females (aged 9 to 14) in a time-sequential design-and evaluate if low RS can predicts depression.
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