Reduced hedonic capacity in major depressive disorder: Evidence from a probabilistic reward task

Abstract

Objective-Anhedonia, the lack of reactivity to pleasurable stimuli, is a cardinal feature of depression that has received renewed interest as a potential endophenotype of this debilitating disease. The goal of the present study was to test the hypothesis that individuals with major depression are characterized by blunted reward responsiveness, particularly when anhedonic symptoms are prominent.Methods-A probabilistic reward task rooted within signal-detection theory was utilized to objectively assess hedonic capacity in 23 unmedicated subjects meeting DSM-IV criteria for major depressive disorder (MDD) and 25 matched control subjects recruited from the community. Hedonic capacity was defined as reward responsiveness -i.e., the participants' propensity to modulate behavior as a function of reward.Results-Compared to controls, MDD subjects showed significantly reduced reward responsiveness. Trial-by-trial probability analyses revealed that MDD subjects, while responsive to delivery of single rewards, were impaired at integrating reinforcement history over time and expressing a response bias toward a more frequently rewarded cue in the absence of immediate reward. This selective impairment correlated with self-reported anhedonic symptoms, even after considering anxiety symptoms and general distress.Conclusions-These findings indicate that MDD is characterized by an impaired tendency to modulate behavior as a function of prior reinforcements, and provides initial clues about which aspects of hedonic processing might be dysfunctional in depression.

Anhedonia and emotional numbing in treatment-seeking veterans: behavioural and electrophysiological responses to reward

“…As Pizzagalli and colleagues (2008) found that the response bias development completed between first and third block was uninformative in their experiment, they further computed reward learning expressed within the first round only. This parameter was derived in the same manner as above, but comparing response bias in the first half of first block with response bias in the latter half of the same block.…”

“…The experimental procedure replicated the probabilistic reward signal-detection task previously designed by Tripp and Alsop (1999) and adapted by Pizzagalli et al (2005, 2008) and Santesso et al (2008) (see Figure 1). In brief, this task presents 300 trials in three blocks.…”

“…Pizzagalli et al (2005) found the expected negative correlation between response bias towards the rewarded stimulus and level of self-reported anhedonic symptoms in a healthy population. In a subsequent study using the same paradigm to study learning in major depressive disorder (MDD) patients and healthy controls, Pizzagalli and colleagues (2008) found that anhedonic symptoms correlated with impairment in the development of response bias towards the frequently rewarded stimulus.…”

“…Employing a paradigm similar to the task constructed by Pizzagalli and colleagues (2008), their study suggested a moderate correlation between reward-based learning (as expressed in response bias due to reinforcement asymmetry) and a well-known event-related potential (ERP) response to obtained rewards (i.e. reward consumption), the Feedback-Related Negativity (FRN) component (Gehring, 2002).…”

“…Further, they indicate FRN as a possible neural correlate or marker of reward functioning. In the present study, we employ a paradigm similar to experiments by Santesso et al (2008) and Pizzagalli et al (2008), comparing reward-learning through signal-detection performance and neural reward response through FRN.…”