Depression is associated with small to medium impairments in reward-processing behavior, including impairments with tasks assessing option valuation, reward bias, and reinforcement learning. This is according to a study in JAMA Psychiatry.
In this retrospective study, researchers from the United Kingdom examined 48 case-control studies that included a total of 1387 healthy controls and 1767 patients with major depressive disorder (mean age, 37.85 years). Only studies that examined reward-processing tasks and compared performance outcomes on these tasks between healthy controls and patients were depression were included in the final meta-analysis.
The studies included in the final meta-analysis used tasks that assessed option valuation (n=9), reward bias (n=6), reward response vigor (n=12), reinforcement learning (n=20), and grip force (n=1). Depression was associated with small to medium impairments in reward-processing behavior across all tasks (SMD = 0.345; 95% CI, 0.209-0.480). In the subcomponent categories, small-to-medium impairments were observed with tasks that assessed option valuation (SMD = 0.309; 95% CI, 0.147-0.471), reward bias (SMD = 0.644; 95% CI, 0.270-1.017), and reinforcement learning (SMD = 0.352; 95% CI, 0.115-0.588).
According to the investigators, there was substantial overall interstudy heterogeneity (τ2=0.15; I2=68%) as well as considerable heterogeneity in the reward bias (τ2=0.16; I2=75%) and reinforcement learning (τ2=0.21; I2=76%) categories.
Limitations of the study included the lack of assessment for response to punishment, the significant overall heterogeneity, and the lack of assessment for anticipation and hedonic effect of rewards.
The investigators concluded that further “research on reward processing may therefore be a credible route to better characterizing mechanistic heterogeneity within depression, as well as potentially highlighting novel targets for treatment.”
Halahakoon DC, Kieslich K, O’Driscoll C, Nair A, Lewis G, Roiser JP. Reward-processing behavior in depressed participants relative to healthy volunteers: A systematic review and meta-analysis [published online July 29, 2020]. JAMA Psychiatry. doi: 10.1001/jamapsychiatry.2020.2139