| Depression is one of the most important and commonly occurred mental disorders. WTO predicted that depression would become the second pathogeny of death and deformity by 2020. The prevalence rate of male in our country was 16.7%, female was 19.5%, the average prevalence age was 25, most occurred between 15 and 19, also between 25 and 29, among which, about 10%-15% had suicidal risk. An international survey at September 8th in 2007 showed that depressive disorder had more serious effects on human beings than angina, arthritis, asthma and diabetes. These researches hint that depressive disorder is an important public health problem needing immediately attention.Previous studies discussed cognitive bias of depression on the base of attention and memory. In the attention studies, most researchers studied from the facilitation of attention, the results of which found that the depressed individuals had the attentional bias for negative stimuli. Just the negative attentional bias led the negative stimuli to be processed firstly and magnified by depressed individuals, which would cause the maintenance and development of depression. This was the facilitation effect theory in depression, but this theory can't explain attentional bias entirely, for example, the difficult attention disengagement phenomenon, the over attention engagement phenomenon, etc., all which hint that the depressed individuals may fail to inhibit negative stimuli.Present study explored depressed individuals from the inhibition aspect of attention, the prevalence and influence factors of depression was analyzed by questionnaire (attribution type questionnaire, BDI, SDS, EPQ, self-esteem, A type behavior and self-efficacy questionnaire), the inhibition characteristics(distracter inhibition, inhibition of return and interfere inhibition) and brain mechanism of attentional bias in depression was discussed by cognitive behavior experiment(negative priming task, cue-target task and Stroop task) and Event-Related Potentials ( ERP ) experiment, the evaluation characteristics and tendency of depressed individuals for emotional stimuli was obtained by emotional faces evaluation task. The following outcomes and conclusions were obtained:1. The prevalence rate of female(χ2=21.194,p=0.000) and junior students(χ2=24.966,p=0.000) was high, the depression score of female(F=3.765,P=0.053) and junior students(F=2.391,P=0.092) was high, the difference was marginal significant.2. Self-esteem, Psychoticism, Extroversion and Neurotic of EPQ, A type behavior and self-efficacy had more influence on depression, the correlation coefficient was between 0.256 and 0.578, they were the independent variables of the best regression equation.3. More positive attributive style, less negative attributive style, positive events inner attribution, negative events outer attribution, would lead less depression.4. In negative priming task, depressed individuals had a deficient distracter inhibition(F=12.95,P=0.000) and excessive facilitation(F=21.50,P=0.000) for negative stimuli in behavior experiment. The characteristicsstic of ERP was that the"depressed"participants had bigger N1 amplitude for happy faces under positive priming condition(F=4.887,P=0.033), the P3 amplitude was bigger for sad faces under positive priming condition(F=4.803,P=0.035) and negative priming condition(F=5.353,P=0.026), which hint that the"depressed"participants have distracter inhibition and facilitation ability for both positive and negative stimuli; the major depressive disorders(MDD) had bigger N1(F=3.056,P=0.055) and P1 amplitude (F=8.86,P=0.000) for sad faces under positive priming condition, bigger P3 amplitude for sad faces under positive priming condition(F=6.011,P=0.004), but smaller P3 amplitude for sad faces under negative priming condition(F=8.983,P=0.000), which hint that the MDD have a deficient distracter inhibition and excessive facilitation for negative stimuli.5. In the cue-target task, when the presentation of stimuli was 1000ms, the characteristics of behavior experiment for depressed individuals was that when the SOA (stimulus onset asynchronies,SOA) was 14ms, the"depressed"participants had the IOR(inhibition of return, IOR) effect for angry faces(F=11.49,P=0.002) and happy faces(F=18.27,P=0.000), MDD had IOR effect for angry faces(F=24.81,P=0.002)and sad feces(F=81.58,P=0.000); when the SOA was 250ms, three groups all had the cue effects for sad faces, but the effects of MDD was much higher than other two groups(F=5.57,P=0.005); when the SOA was 750ms, the never-disordered controls(NC) ( F=17.30 , P=0.000 ) and the"depressed"participants( F=2.97,P=0.094)had the IOR effects for sad faces, while the MDD had cue effect for sad faces(F=64.64,P=0.000), and had IOR effect for angry faces. The characteristics of ERP was that when the SOA was 750ms, the"depressed"participants had bigger P1 amplitude than NC for sad faces in valid cue condition(F=52.795,P=0.068), which hint that the cue effect of"depressed"participants for sad faces is bigger than NC; MDD had bigger P1(F=7.807,P=0.001)and P3 amplitude(F=3.85,P=0.024)for sad faces as a cue, smaller P3 amplitude for sad faces in invalid cue condition(F=6.938,P=0.002), smaller P3 amplitude for happy faces in valid cue condition(F=3.49,P=0.036), which hint that the MDD have excessive facilitation for sad faces as a cue, deficient inhibition for target after sad faces, and IOR effects for targets after happy faces.6. In Stroop task, the characteristics of behavior experiment was that the"depressed"participants had deficient interfere inhibition for supraliminal positive words(t=2.321,P=0.027) and subliminal negative words(t=1.968,P=0.058), MDD had deficient interfere inhibition for supraliminal negative words(F=3.293,P=0.042).The characteristics of ERP was that the MDD had smaller N1 amplitude for sad faces in both hemispheres(F=4.575,P=0.015)(F=3.808,P=0.029), which hint that the MDD have deficient interfere inhibition for supraliminal negative words.7. In evaluation task for emotional stimuli, the depressed individuals lacked the ability to perceive positive stimulu(sF=10.91,P=0.000), magnified the negative stimulu(sF=8.80,P=0.000), and had an excessive facilitation for negative stimulus. Among them, the first one is a state marker of depression, the latter two are the traitlike characteristics of depression.Present study observed the attentional bias and brain activation characteristics of depressed individuals systematically from the inhibition aspect of attention, and the evaluation characteristics of depressed individuals for emotional stimuli. So, on the one hand, present study has deepen the theory research of cognitive bias in depression, which will be beneficial to understand the development of depression and attentional bias of depressed individuals; On the other hand, it would offer theoretical basis for cognition therapy of depressed individuals, that is to say depressed individuals can be cured by intended neglecting and effective inhibiting negative stimuli. |
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