In recent study published in Psychological Medicine, my colleagues and I have found distinct neural alterations during monetary and natural reward processing in patients with depression compared to healthy controls. From a neuroimaging meta-analysis of published fMRI studies in patients with depression and a total of 1,277 participants, the study provides the first evidence that reward alterations in depression differ depending on the type of reward.
For years, researchers have documented reward dysfunctions in depression to mainly occur in the striatum, a brain region strongly involved in reward and motivational processes. However, there are different types of rewards, including natural rewards (e.g. good food or your favorite song) and more abstract or learned rewards such as money. While alterations in reward and motivational processes are core symptoms of depression it has not been examined if the brain basis of natural and monetary rewards differ in the disorder.
Depression is a devastating mental disorder that is characterized by prolonged periods of sadness and anhedonia (loss of interest in almost all of daily life activities). We found interest in this topic because depression is a leading cause of disability affecting millions of people worldwide and there is need to establish determine the neurobiological underpinnings that can inform new treatments.
Our research team, including members from The University of Hong Kong and the University of Electronic Science and Technology of China, conducted a neuroimaging meta-analysis encompassing all suitable previous studies that used fMRI to examine the brain basis of reward alterations in depression. We found that patients with depression exhibited generally decreased activation in the subgenual anterior cingulate cortex and striatum during receipt of all reward types.
However, depression patients showed separable alterations during monetary and natural rewards in the right ventral striatum and the dorsal striatum, respectively. The striatum is a quite heterogeneous brain region and the ventral and dorsal part have distinct functions, such that the ventral striatum is primarily involved in reward and motivational processing while the dorsal striatum is involved in motor and cognitive control. Further network level analyses and behavioral decoding analyses confirmed these conclusions.
The present results indicate that distinguishable neurofunctional alterations may neurally mediate reward processing alterations in depression, in particular, with respect to monetary and natural rewards. Given that natural rewards prevail in everyday life, our findings suggest that reward-type specific interventions are warranted. Moreover, the results challenge whether findings from studies on reward alterations that have been observed in monetary tasks can accurately capture reward dysfunctions in everyday life.
Despite promising findings, the study has some limitations and points to open questions. For instance, the study also found that anti-depressive medication may affect the brain alterations in depression. Future studies are therefore required to better understand if treatment with anti-depressive medication affects brain processing of natural and monetary rewards different in depression.
The study, “Distinct neurofunctional alterations during motivational and hedonic processing of natural and monetary rewards in depression – a neuroimaging meta-analysis,” was authored by Mercy Chepngetich Bore, Xiqin Liu, Xianyang Gan, Lan Wang, Ting Xu, Stefania Ferraro, Liyuan Li, Bo Zhou, Jie Zhang, Deniz Vatansever, Bharat Biswal, Benjamin Klugah-Brown and Benjamin Becker.