Worth the 'EEfRT'? The effort expenditure for rewards task as an objective measure of motivation and anhedonia

• Type of Material: Article
• Authors: Michael T. Treadway, Emory University; Joshua W. Buckholtz, Vanderbilt University; Ashley N. Schwartzman, Vanderbilt University; Warren E. Lambert, Vanderbilt University; David H. Zald, Vanderbilt University
• Language: English
• Date: 2009-08-12
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: © 2009 Treadway et al.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0006598
• Title of Journal or Parent Work: PLoS ONE
• ISSN: 1932-6203
• Volume: 4
• Issue: 8
• Start Page: e6598
• End Page: e6598
• Grant/Funding Information: This work was funded by Vanderbilt University and NIDA grant 5R01DA019670 awarded to D.H.Z..
• Keywords: Female; Analysis of Variance; Adult; Male; Depressive Disorder, Major; Humans; Motivation
• Research Categories: Biology, Neuroscience; Psychology, Behavioral; Health Sciences, Mental Health

Abstract

Background: Of the putative psychopathological endophenotypes in major depressive disorder (MDD), the anhedonic subtype is particularly well supported. Anhedonia is generally assumed to reflect aberrant motivation and reward responsivity. However, research has been limited by a lack of objective measures of reward motivation. We present the Effort-Expenditure for Rewards Task (EEfRT or "effort"), a novel behavioral paradigm as a means of exploring effort-based decision-making in humans. Using the EEfRT, we test the hypothesis that effort-based decision-making is related to trait anhedonia. Methods/Results: 61 undergraduate students participated in the experiment. Subjects completed self-report measures of mood and trait anhedonia, and completed the EEfRT. Across multiple analyses, we found a significant inverse relationship between anhedonia and willingness to expend effort for rewards. Conclusions: These findings suggest that anhedonia is specifically associated with decreased motivation for rewards, and provide initial validation for the EEfRT as a laboratory-based behavioral measure of reward motivation and effort-based decision-making in humans.