Identifying risk factors for depression: genetic variations and psychophysiological measures of initial reward responsiveness
Date
2016
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Publisher
University of Delaware
Abstract
Despite the large and far-reaching impact of depression, little is known about the pathophysiology associated with the disorder. This is due in part to limitations of the current diagnostic system, which includes considerable symptom heterogeneity within diagnostic categories. To address this issue, the Research Domain Criteria (RDoC) initiative, introduced by the National Institute of Mental Health, has proposed that psychopathology research include measures that span multiple units of analysis to examine function across several domains. The goal of the present study was to build and evaluate a risk model for depressive symptoms that included genetic risk and multiple psychophysiological measures of initial reward responsiveness, an RDoC construct that is related to depression. A novel monetary incentive delay task was developed to clarify the unique information provided by EEG and fMRI measures of initial reward responsiveness and to elucidate the impact of context on these responses. EEG and fMRI measures of initial reward responsiveness were related, but each provided unique information, highlighting the importance of including both in future studies. Additionally, these two psychophysiological measures were influenced by context in a way that suggests they are sensitive to the amount of knowledge provided, highlighting a potential strategy for further examination and classification of psychopathology. Overall, the risk model poorly predicted depressive symptoms: only the fMRI measure of initial reward responsiveness, but not the EEG measure or genetic risk, was related to depressive symptoms. These results highlight the limited value of genetic risk profile scores in predicting depressive symptoms as well as the role that symptom severity and gender may play in moderating the relationship between psychophysiological measures of initial reward responsiveness and depressive symptoms.