The Study Of Self-representation And Self-discrepancy Among Subthreshold Depressive College Students

Objective:Subthreshold depression refers to more than two weeks most of everyday there are more than 2 kinds of symptoms of depression,with a certain degree of social dysfunction,but not up to DSM-IV(the diagnostic and Statistical Manual of mental disorders Fourth Edition)diagnostic criteria for major depressive episodes / depression disorder.Based on the self-reference processing paradigm,this study explored the pathological mechanism of subthreshold depression on actual/ideal self-representation of processing bias,self-discrepancy and their related ERP.Methods: First,college students of depressed tendencies were screened for1600 college students of Guangdong province by convenience sampling method;Second,within 1-2 weeks using the diagnostic and statistical manual of mental disorders(the Structured Clinical Interview for DSM,SCID)for the diagnosis and differential diagnosis,further screening out subthreshold depression(SD)group and healthy controls(HC)group of college students;Finally,32 people of subthreshold depression group and 30 people of healthy control group(a total of 62 college students)were invited to participate in the formal experiment.The formal experiment was based on the self-reference processing paradigm using positive adjective and negative adjective,during theexperiment the subjects were asked the subjects to judge whether the words fit the self-conditions(actual-self or ideal-self)andpress corresponding button as soon as possible.A mixed design of 2(self-conditions:actual-self,ideal-self)× 2(words valence: positive,negative)× 2(groups: subthreshold depression group,healthy control group),behavioral and EEG data statistical analysis was respectively conducted after the experiment:(1)All behavioral datas of reaction time and response bias were analyzed in orderto compare cognitive processing of self-representation(actual-self and ideal-self)and self-discrepancy among two groups.(2)The EEG data of 51 effective subjects(25subjects of subthreshold depression group and 26 subjects of healthy controls group)were analyzed offline,including P2 and LPC electrical components of stimulus/lexical presentation phase,as well as N1 and LPC electrical components of lexical decision phase(self-conditional presenting).Results:(1)The statistical results of the behaviral data indicated that:On the reaction time,for the health control group,the response time to the positive words were longer than the negative words.For subthreshold depression group,the response time to the negative words was longer than the positive words under the condition of actual-self,but there was no significant difference between positive words and negative wordsunder the condition of ideal-self.On the response bias,both under the condition of actual-self and ideal-self,the response bias of the subthreshold depression group was significantly more negative than healthy control group;actual-ideal self-discrepancy of the subthreshold depression group was significant greater than the healthy control group.(2)The statistical results of the EEG data indicated that:In thestimulus/lexical presentation phase:P2: The results showed that the negative words elicited P2 amplitude significantly greater than the positive words,but there was no significant difference between group.LPC: The results showed that positive and negative words did not elicit significant difference in the volatility of LPC for healthy control subjects;for the subthreshold depression group,negative words elicited significantly greater LPC amplitude thanpositive words.In lexical decision phase(self-conditional presenting):N1: The results showed that under the condition of ideal-self elicited greater N1 amplitude than actual-self.For the health control group,N1 amplitude was not influenced by the valence of words.While for subthreshold depression group,the negative words elicitedlarger N1 amplitude than positive words.LPC:The results showed that the reaction to positive words elicited greater LPC amplitude than the reaction to negative words.Ideal-self condition elicited greater LPC amplitude than actual-self condition significantly.Subthreshold depression group elicitedgreater LPC amplitude than the healthy control subjects significantly.Conclusions:(1)The subthreshold depressive college students have self-referential bias.They have more negative actual-self concept,and a higher ideal-self level than healthy college students.(2)Actual-ideal self-discrepancy of subthreshold depressive students in college is larger than healthy college students,which suggested that the actual-idealself-discrepancy is related with depression.(3)Compared with the actual-self,ideal-self condition induces greater early attention and advanced evaluation processing.(4)The subthreshold depressive collegestudents show negative bias on advanced processing,healthy college students show advanced negative bias on advancedevaluation processing.(5)The subthreshold depressive college students show excessively self-focused,and they allocate more resources to the late processing of emotional stimuli(positive and negative words)than healthy college students.