Affective Predictors of Disrupted Reward-Seeking in Depression
thesisposted on 2015-07-21, 00:00 authored by Sophia DelDonno
Background: Anhedonia, or the diminished anticipation and pursuit of reward, is a core symptom of major depressive disorder (MDD). Trait behavioral activation (BA), as a proxy measure of anhedonia, and behavioral inhibition (BI) may moderate the relationship between MDD and reward-seeking. The present studies (Study 1 and Study 2) probed for reward learning deficits, potentially due to aberrant BA and/or BI, in individuals with active or remitted MDD compared to healthy controls (HC). Methods: Active MDD (in Study 1) and remitted MDD (in Study 2) participants completed the modified monetary incentive delay task (mMIDT), a behavioral reward-seeking measure whose response window parameters were individually titrated to theoretically elicit equivalent accuracy between groups. Participants completed the Behavioral Inhibition Scale and Behavioral Activation Reward-Responsiveness and Drive Scales. Results: Despite individual response speed titration, active MDD participants won significantly less money than HCs. Higher Reward-Responsiveness scores predicted a greater amount won, whereas Drive and BI did not predict performance. Remitted MDD participants did not differ from controls on mMIDT performance, and trait measures of BA or BI did not predict r-MDD performance. Discussion: These results suggest that diminished reward-responsiveness may contribute to decreased motivation and reward pursuit during active MDD, and that reward learning is intact in remission. Understanding individual reward processing deficits in MDD may inform personalized intervention for alleviating anhedonia and motivation deficits in select active MDD patients. Limitations include small sample sizes, different age ranges in the two studies, and collecting the data during fMRI in Study 1 but not Study 2.