Neural Mechanisms Underlying Depression-related Attentional Control Impairment

BackgroundAttentional control impairment is an important risk factor for the onset,development,and maintenance of depression.Several studies have revealed the relationship between attentional control impairment and depression in patients with depressive disorders and bipolar disorders,but existing behavioral studies as well as brain imaging studies have difficulty distinguishing between specific processes of attentional control and lack system measures of general and emotional attentional control,such that the cognitive neural mechanisms of depression-related attentional control impairment are unclear.In addition,the application of attentional control theory in depressed populations still needs further validation.PurposeBased on attentional control theory,to understand the characteristics and impairments of general and emotional attentional control in major depression disorder patients(MDD),bipolar disorder patients(BD)and healthy controls(HC)under different cognitive load.To reveal the intrinsic cognitive processes of attentional control associated with depression.Participants and methodsTwenty-four patients with MDD,25 patients with BD and 57 individuals with HC were studied under general and emotional stimulus interference using a low cognitive load line visual search task and a high cognitive load face visual search task with the event-related potential technique.Based on the permutation test for One-way ANOVA and repeated measures ANOVA were used to test for differences between groups and conditions,and Spearman’s correlation coefficient was used to evaluate the correlations between the variables,and p-values for multiple comparisons were corrected for FDR.Results1)Patients with MDD and BD had significantly lower scores on the attentional control scale than the HC group(p=0.042).2)In the line visual search task,there was no significant difference in accuracy between the MDD and BD groups and healthy controls(p=0.111),while the overall reaction time was longer in the MDD and BD groups compared to HC group(p=0.053),and there was no significant difference between the MDD and BD groups(pFDR=0.211).Mean amplitude of target-evoked N2pc component was weaker in both the MDD and BD groups compared to the HC group(HC:1.63-μV,BD:-1.03μV,MDD:-1.15 μV,p=0.079)in the distractor-absent condition.In contrast,distractor-evoked Pd component was absent in the MDD and BD groups.Distractor-evoked N2pc component was absent in all groups.(3)In the distraction-absent and color-distractor conditions of the face visual search task,relative to the HC group,the MDD and BD groups had slightly lower accuracy and longer reaction times in both conditions(p1=0.003,p2=0.047).Although the statistical data showed no significant differences,numerically,mean amplitude of the target-evoked N2pc component was smaller in both the MDD and BD groups than in the HC group(HC:-1.76 μV,BD:-1.38 μV,MDD:-1.20 μV,p=0.047).(4)In the color-distractor and each emotional-distractor conditions of face visual search task,there was no significant difference between the MDD and BD groups in overall accuracy and reaction time(pFDR>0.05).Compared with the HC group,it showed lower accuracy and longer reaction time(p1=0.003,p2=0.047).ERP results showed that the interaction effect between group and trial conditions was significant(p=0.063).The results indicated that the target-evoked N2pc amplitude of colordistractor and anger-distractor conditions was greater in the BD group than in the MDD group,while the target-evoked N2pc amplitude of happy-distractor and sad-distractor conditions was smaller than MDD group.The target-evoked N2pc amplitude was greater in the HC group than in the MDD and BD groups under all trials.Although statistical tests showed no significant differences,numerically,the overall mean amplitude of distractor-evoked Pd components in the MDD and BD groups were smaller than that in the HC group(HC:0.32 μV,BD:0.25 μV,MDD:0.13 μV,p=0.340).5)The scores of attention control scale were negatively correlated with behavioral reaction time(rs:-0.21～-0.24,p<0.05),and negatively correlated with the targetevoked N2pc amplitude(rs:-0.20～-0.23,p<05),behavioral response time was significantly positively correlated with target-evoked N2pc average amplitude(rs:0.20～0.23,p<0.05).Conclusions1)Patients with MDD and BD had general attentional control impairments,and behavioral performance was mainly characterized by decreased processing efficacy and no effect on operational performance,with specific intrinsic cognitive processing as depressed individuals attenuated top-down attentional inhibition of distractors and top-down attentional selection resources to targets.As cognitive load levels increased,both processing efficacy and operational performance decreased,and top-down attentional selection resources to targets are limited.The bottom-up attentional selection process was not impaired in depressed individuals.2)Patients with MDD and BD had emotional attentional control impairments,decreased processing efficacy and operational performance,and overall top-down attentional resources were insufficient.Patients with MDD showed less attention to happy and sad faces,and patients with BD showed more attention to happy faces.This study systematically reveals the cognitive neural mechanisms of attentional control impairment in depressed individuals under different cognitive load and provides a scientific basis for the prevention and treatment of depressed individuals.