An Event-Related Potential Study Of Directed Forgetting In Depressed Individuals Under Hypnosis

Background: Depression is one of the most common psychological disorders.Its main clinical features are significant and lasting sadness,low self-esteem and depression,and may lead to suicidal intention or behavior in severe cases.Many studies have shown that depression have difficulty in forgetting negative materials,and this impairment of inhibitory function may lead to impaired recovery of depression.In recent years,studies have shown that hypnotic suggestion can affect memory,enhance memory for learning materials,improve negative episodic memory,and affect cognition and attention bias.Until now,we don’t know whether depressed individuals have difficulties in forgetting negative memories under hypnosis as well.This study aims to investigate the neural mechanism of directed forgetting in depression under hypnosis using event-related potential(ERP),which will help us to better understand depression,the neural mechanism of memory suppression and intentional forgetting in depression under hypnosis,and also help us to develop new treatment methods.Methods: In this study,the Beck Depression Inventory(BD-II)was used to screen participants,including 30 depression prone subjects with scores greater than or equal to 14 points and 30 normal control subjects with scores less than 14 points.The hypnotic technique was used to explore the behavioral data of individuals with depression tendency to complete the directed forgetting paradigm under hypnosis,and the event-related potential(ERP)technique was used to explore the underlying neural mechanism.To compare the results of directed forgetting between depressed individuals and normal individuals under hypnosis and its neural mechanism.Hypnotic susceptibility was analyzed as a covariate and selected the components of P1,P2,and LPP related to words and the components of P1,N2,and P3 related to instructions for analysis.Results: In the behavioral results,it is found that the main effect of cues(p = 0.002)was significant in behavioral results in the depression and normal control groups under hypnosis,and the interaction of cues and type of words was significant(p=0.017).The recognition rate of negative words was significantly higher than that of neutral words(p<0.001)during the forgetting cues.The interaction of type of words,type of cues and group was significant(p=0.043).During the forgetting cues,the recognition rate of negative forgotten words was significantly higher than that of neutral forgetting words in both depression group(p=0.007)and control group(p<0.001).The response time of forgotten words in the depressed group was significantly higher than that of remembered words when viewing negative words(p=0.028).In terms of word-related ERP results,the main effect of the group on the P1 amplitude was significant,the P1 amplitude of the depression group was significantly lower than that of the control group(p=0.012),the P1 amplitude evoked by different types of cue in control group was significantly different(p<0.001),there was no significant effect in depression group(p=0.811).The main effect of word type on P2 amplitude was significant,and the amplitude of negative words was greater than that of neutral words(p=0.043).The main effect of LPP amplitude was significant,and the LPP amplitude of the depression group was significantly greater than that of the control group(p=0.038).The cue-related N2 showed significantly greater amplitude in depression group during forgetting cues than remembering cues(p=0.001).Hypnotic susceptibility as a covariate had a significant effect on cue-related components(p<0.5).Conclusion: We found that under hypnosis,both depression and normal controls showed significant directed forgetting effects,but the hypnotic state inhibited excessive attention to negative information in the depression.In terms of ERP results,depressed subjects displayed lower P1,P2 and larger LPP amplitudes when viewing negative words,and larger amplitudes of N2 when forgetting negative words.We also found that hypnosis has an impact on directed forgetting outcomes,especially on the ERP components associated with cues,and we believe that the instructions of the directed forgetting paradigm play a hypnotic suggestive role under hypnosis.From the results of this experiment,hypnosis does affect the ability and outcome of directed forgetting in depressions,which may provide a theoretical basis for our future intervention research on hypnosis for depression.