Anomaly Reward Processing Of Trait Anhedonia And Intervention Study Of HD-tDCS

Objective: Numerous studies have shown that anhedonia is also present in the non-clinical population and impinges on their daily life and behavior.Currently,there is no effective way to improve anhedonia in the non-clinical population.Therefore,it is important to promote the application of high definition transcranial direct current stimulation(HD-TDCS)in the non-clinical population.In this study,the effects of HD-t DCS on the improvement of anhedonia symptoms and reward processing abnormalities were confirmed by measuring the relevant scales in individuals with trait anhedonia,observing the performance of monetary incentive delay(MID)task and the changes in the neural mechanism.Methods: 53 subjects in the trait anhedonia group and 24 subjects in the normal control group were collected in this study.The Chinese revised Temporal Experiential Pleasure Scale(TEPS)was used to evaluate the difference in the degree of anhedonia between normal and anhedonic individuals.The difference in reward sensitivity was evaluated by the performance of the two groups in the monetary incentive delay(MID)task.The difference of electrophysiological activity between the two groups was studied by the event-related potentials(ERPs)when they completed the monetary incentive delay task.In this study,SPSS 16.0 was used to analyze the data,one-way analysis of variance was used to analyze the anhedonia scale,and repeated measure analysis of variance was used to analyze the behavioral and ERPs data.In this randomized,double-blind trial,Fifty-three subjects with trait anhedonia received HD-t DCS intervention.53 subjects were randomly assigned to the true stimulus group(n=28)and the sham stimulus group(n=25).The true stimulus group received cathode HD-t DCS stimulation with 2m A current for 20 minutes every day for 10 consecutive days,while the sham stimulus group received cathode HD-t DCS stimulation with 0m A current,namely,received the sham stimulus.The Chinese revised Temporal Experiential Pleasure Scale(TEPS)was used to evaluate the improvement of anhedonia before and after intervention in both groups.The change of reward sensitivity before and after the intervention was evaluated by the performance of the two groups in the monetary incentive delay(MID)task.The change of electrophysiological activity before and after the intervention was studied by using the event-related potentials(ERPs)when the two groups completed the monetary incentive delay task.In this study,SPSS 16.0 was used to analyze the data,and chi-square test,independent sample t test,repeated measure variance analysis were used for statistical analysis of relevant scales,behavioral and ERPs data..Results: The TEPS scores and TEPS consummatory anhedonia subscale(TEPS-con)scores of trait anhedonia group and normal control group were significantly different.By observing the performance of the monetary incentive delay(MID)task on the reaction time index,it was found that there were significant differences between the two groups under the condition of no reward,low reward and high reward,and the trait anhedonia group was slower than the normal control group in response to reward.By observing the performance of the response time index in the monetary incentive delay(MID)task,it was found that the two groups of subjects had significant differences in the low reward and high reward condition,while the two groups had no significant differences in the no reward condition.The results of the study on the event-related potentials of the participants completing the monetary incentive delay task showed that the cue-Rew P of the trait anhedonia group was significantly different from the normal control group under the condition of high reward,and cue N2 and cue-P3 were significantly different from the normal control group under the condition of low reward.It was found that the amplitude of cue-Rew P and cue-P3 in trait anhedonia group showed a corrected trend,while the amplitude of cue-N2 showed a more negative trend.There was no significant difference between the cue-P3 and CNV amplitude and the normal group.The total scale score of TEPS and the TEPS-con subscale score of the true stimulus group were significantly different before and after intervention,while the scale scores of the sham stimulus group were not significantly different before and after intervention.After intervention,TEPS and their subscale scores decreased significantly and BDI scores increased significantly in the true stimulus group,while scores in the sham stimulus group did not change significantly,suggesting that 10 consecutive days of HD-t DCS targeting the right orbitofrontal lobe could improve characteristic anhedonia.The performance of the subjects in the monetary incentive delay(MID)task was observed.It was found that the difference between the two groups was significant before and after the intervention in the condition of no reward and high reward,and the response time of the subjects was significantly reduced after the intervention.The results of the study on the event-related potential of the subjects completing the monetary incentive delay task showed that the amplitude of cue-Rew P and cue-N2 in the true stimulus group was significantly different before and after the intervention,and the amplitude of cue-Rew P and cue-P3 had a more negative trend,and the amplitude of cue-N2 and CNV had a more positive trend.Conclusion:Compared with normal people,individuals with trait anhedonia showed increased depressive mood,slow response to reward and decreased accuracy of reward.Individuals with trait anhedonia showed a corrected trend of cue-Rew P and cue-P3 amplitude,and a more negative trend of cue-N2 amplitude.These evidences prove that the reward processing mechanism of individuals with trait anhedonia is abnormal,and the importance of intervention methods to improve the reward processing mechanism of non-clinical people becomes more prominent.After receiving HD-t DCS stimulation,the anhedonia symptoms of trait anhedonia subjects were improved and the response to reward decreased.The amplitude of cue-Rew P and cue-P3 decreased,and the amplitude of cue-N2 and CNV increased,and the sensitivity to reward gradually became normal.These evidence proved that orbitofrontal region can regulate reward processing in anhedonia patients,and OFC-targeted HD-t DCS stimulation can improve the time characteristics of reward processing and abnormal sensitivity to reward in trait anhedonia individuals.