Cognitive Function And EEG Features In Indiciduals With Depression And Bipolar Depression

Objective: The differential diagnosis and treatment of Unipolar Depression Disorder(UPD)and Bipolar depression disorder(BPD)is a clinical problem.In this study we analyzes the differences in cognitive function and EEG features between UPD patients and BPD patientso explore the differences and connections between the pathological mechanisms of two groups,and search for objective biological indicators.Method: The subjects were outpatient patients collected by the research group of mood disorder from December 2019 to September 2021 at Xiangya Second Hospital of Central South University(National Clinical Medical Research Center for Mental and Psychological Disorders),who met the diagnostic criteria for depressive disorders and bipolar disorder depressive episodes(DSM-5),and a total of 140 patients were included,including 70 with depressive disorders and 70 with bipolar disorder depressive episodes.The severity of depression was assessed using the Hamilton Depression Scale(HAMD-17)and Self-rating depression scale(SDS).The Hamilton Anxiety Scale(HAMA)was used to assess the severity of anxiety symptoms,the Neurocognitive Test were used to assess patients’ cognitive function,and baseline resting EEG and task EEG(face-word stroop experiment)data was completed at baseline.Follow-up was conducted at the end of 2 week,4 week,and 8 week after the baseline assessment.HAMD-17 and neurocognitive tests were evaluated at every follow-up point.We compared the differences and changes in clinical data and neurocognitive test data between the two groups at baseline and various follow-up time points.And analyzing EEG data from four aspects: 1.we compared the average power of each band(δ-γ)of 64 electrode points in UPD group and BPD group,to study the differences of the EEG power spectrum between two groups;2.use the EEGLAB microstate analysis plugin to analyze EEG microstate data and compare their EEG microstate characteristics;3.using resting state EEG data to count envelope connectivity matrix,then to build a whole brain functional network.The brain functional network of two groups were compared;4.using the ERPLAB toolbox,we extracted the N450 and SP components from the preprocessed task state EEG data,to study the differences in emotion processing function between two groups when facing emotional conflicts.Results:1.Differences in cognitive function between UPD and BPD: BPD have more severe cognitive impairment than UPD(P<0.05).After 8weeks of drug treatment,compared with BPD group,the processing speed(F(1,69)= 4.302,P = 0.045),continuous attention(F(1,69)= 7.855,P = 0.009)and Inhibitory control ability(F(3,67)= 5.594,P = 0.001)of the UPD group in the wiring test improved more significantly.2.The result of the EEG power spectrum analysis: The absolute efficacy of electrode points C3,O2,FP1,FP2 and F8 in the δ band is higher in the BPD group than in the UPD group(P< 0.05);higher absolute efficacy of θ band in the C3,FP2 and F8 of BPD groups compared to the UPD group(P<0.05).the absolute efficacy of electrode points C3,FP2 and F8 in the α band is higher in the BPD group than in the UPD group(P<0.05).3.The result of the EEG microstates analysis: Compared to patients with BPD,UPD patients have longer average duration of EEG microstates and fewer occurrences per unit time(P<0.05).No significant difference was found in the percentage of microstate time coverage and transition category between the two group(P>0.05).4.The result of the function connectivity analysis: On the full frequency band PEC,the UPD group has a sub-network with enhanced functional connectivity,including 44 significantly different connectivity edges.Further analysis shows that the dorsal attention network appears more frequently than other brain networks,with the highest frequency appearing in the posterior part of the right hemisphere’s inferior frontal gyrus(12 times).In the beta band,the UPD group has a sub-network with enhanced functional connectivity,including 32 significantly different connectivity edges.Further analysis finds that the left supramarginal gyrus appeared most frequently(6 times).5.The results of EEG face-word stroop analysis: when facing emotional stimuli,the N450 amplitudes in the left frontal lobe(F=8.34,P=0.018),right frontal lobe(F=9.65,P=0.003),and middle frontal lobe(F=12.75,P=0.001)of the UPD group were significantly higher than those in the BPD group.The N450 latent period in the middle frontal lobe of the UPD group was shorter than that of the BPD group(F=12.75,P=0.001).There is a significant difference in the SP component of the right parietal lobe between two groups,and the UPD group is significantly higher than the BPD group(F=11.13,P=0.001).Conclusion:Our study found that cognitive impairment was more severe and got worse treatment improvement in the BPD group,while emotional conflict dysfunction was more severe in UPD patients;In addition,in the analysis and comparison of resting state EEG characteristics,we found that the absolute power,microstate characteristics and functional connectivity characteristics showed different characteristics in two groups,indicating that EEG physiological characteristics have potential to become an important indicator to distinguish BPD and UPD patients.