Research On Neural Brain Activation Of Anticipatory Versus Consummatory Anhedonia In MDD

Objective:Major depressive disorder (MDD) is a common mood disorder which has a high leading cause of death and disability. However, the diagnostic, comorbidity, etiological and symptom heterogeneity of MDD lead to difficulties of identifying neurobiological mechanisms and finding more effective treatments. So it is essential to distinguish between motivational and consummatory anhedonia. Emerging evidence from neuroimaging studies indicates that the dysfunction of the reward system may be the potential neural basis of anhedoina.Methods:The monetary incentive delay (MID) task was designed by Diego A. Pizzagalli, which has been used in prior study and well elicited neural responses to monetary incentive anticipation and outcomes both in healthy people and MDD individuals. Participants were assessed by the 21-item HAM-D and HAM-A to investigate the degree of depression and anxiety. And all participants also accomplished a Temporal Experience of Pleasure Scale which distinguishes between motivational and consummatory pleasure. Then 15 participants with major depression, and 15 well matched control subjects finally finished the study.Results:(1)The main effect both in group (F=2.121,p=0.167) and cue (F=3.200,p=0.074) were not significant, and there were no interaction effect (F=1.900,P=0.189) between them.The results indicated that the comparison and major depression groups showed similar overall reaction time. There are statistical significance between two groups in the 21-item HAM-D (T=15.474,p<0.01) and HAM-A scales (T=9.240, p<0.01). We found that anticipatory anhedonia (T=2.429,p<0.05)and consummatory anhedonia (T=-2.680,P<0.05) had statistical significance between paitents and controls in TEPS.(2)Compaired to MDD patitents,The control group show increased activation in the bilateral caudate, nucleus accumbens, globus pallidus(near to putamen), and the posterior part of the anterior cingulated in reward anticipation (reward cue minus no-incentive cue). Relative to MDD patitents, the control group show increased activation in the right anterior cingulate (near to orbitofrontal cortex) in reward outcome (gain minus no-change feedback).(3)We found the relationship between anticipatory anhedonia of TEPS and anticipatory reward processing in posterior cingulate (r=0.493,p<0.05). We also found the relationship between consummatory anhedonia of TEPS and consummatory reward processing in anterior cingulate (r=0.381,p<0.05)Conlutions:(1)There were anticipatory anhedonia and consummatory anhedonia in MDD. (2)The finding suggested the reward liking was most in sub-cortical structures while reward wanting was in cortical regions in MDD.(3)We found that difference neural areas had decreased activated in the anticipatory and consummatory phase in MDD. (4)The neural areas of posterior cingulated is related to anticipatory anhedonia, while anterior cingulate is related to consummatory anhedonia.