The Effects Of RTMS To Treat Anhedonia In MDD

Objective:Major depressive disorder(MDD)is a common mood disorder worldwide,which has a high leading cause of death and disability.Anhedonia,as one of the core features of depression in the DSM-IV diagnostic criteria,is drawing increasing attention.Anhedonia,which might be the most possible endophenotype of depression,is redefined by Treadway and his colleagues as two subtypes :anticipatory anhedonia and consummatory anhedonia,which suggest a disruption of the appetitive and consummatory aspects of reward.Anticipatory anhedonia means that the motivation to get reward is decreased,however,consummatory anhedonia means that the diminished experience of pleasure of getting reward.A large number of researches have demonstrated that Repetitive transcranial magnetic stimulation(rTMS)has an antidepressant effect in the pre-clinical and clinical settings.But,the brain structure regulating the two anhedonia is different.So,based on the intervention studies of rTMS to depression and the neural network of two anhedonia subtypes,we examined the effects of low-frequency rTMS to the Frontopolar cortex/Brodmann area 10(FPC/BA10)to treat anhedonia in MDD,and further studied which subtype is improved.The curative effect is measured by psychological scales and ERP(Event Related potentials).We hope these results can be popularized to the clinical treatment.Methods: The participants were a series of 44 inpatients with MDD,who were randomly divided into two samples,one was the experimental group(n=21),the other one was control group(n=23).The experimental group was provided 20 sessions of low-frequency FPC-rTMS,all the patients were provided pharmacological treatment in the conventional dosage and regularly consulted the doctor.Following initial clinical assessment,patients underwent ERP and a baseline psychological assessment.During treatment,patients completed psychological measures at 4,20 weeks,which includes SHAPS(Snaith-Hamilton Pleasure Scale),TEPS(Temporal Experience of Pleasure Scale),HAMD-17 and HAMA to investigate the degree of anhedonia and depression and anxiety.TEPS has two factors,which are anticipatory and consummatory factors.At 4 weeks,all the subjects completed the ERP experiment,a Two Door Task,that dissociates anticipatory and consummatory phases of reward processing,P300 and FRN(feedback-related negativity)can be as the signals of anticipatory anhedonia and consummatory anhedonia.All the psychological datum and amplitudes of ERP were analyzed using repetitive measure variance analysis across two groups.Results:(1)Psychological measurements resultsThere were significant time effect(p<0.001)and interaction effect between group and time(p<0.05)on HAMD-17 and HAMA,The scores at 20 weeks were significantly lower than the baseline(p<0.001)and 4 weeks(p<0.001),and the scores at 4 weeks were significantly lower than the baseline(p<0.001),at 20 weeks the subjects in the experimental group got lower scores than the control group(p<0.05).These results have proved the effects of FPC-rTMS to treat depression.As for the SHAPS,the main effect both in group(p < 0.05)and time(p<0.001)were significant,what's more,the scores at 20 weeks were significantly lower than the baseline(p<0.001)and 4 weeks(p<0.001),and the scores at 4 weeks were significantly lower than the baseline(p<0.001),at 20 weeks the subjects in the experimental group got the lower scores than the control group(p<0.01).As for TEPS,TEPS-ant and TEPS-con,there were significant time effect(p<0.05)and interaction effect between group and time(p<0.01).The scores at 20 weeks were significantly higher than the baseline(p<0.05)and 4 weeks(p<0.001),and the scores at 4 weeks were significantly higher than the baseline(p<0.001),at 20 weeks the subjects in the experimental group got the higher scores than the control group(p<0.05).These results have proved the effects of FPC-rTMS to treat anhedonia.(2)ERP data resultsThere were no significant time effect(p=0.951)and group effect(p = 0.285)on P300 amplitudes.And,the time effect(p<0.01)was significant on FRN amplitudes,which was smaller posttreatment.However,there was no group effect(p=0.207).Conclusions :(1)FPC-rTMS exerts long-lasting effects to treat depression and anxiety.(2)FPC-rTMS exerts long-lasting effects to treat anhedonia.