Study On The Characteristics Of Intestinal Flora And Its Correlation With Depressive Symptoms In Patients With First Episode Depression

Objective:This study took normal people and first-diversity depression patients as the research objects,compared the differences of gut microbes between depression patients and normal people,explored the characteristics of gut microbes in depression patients,and provided a theoretical basis for the pathogenesis and clinical diagnosis of depression the treatment provides a certain reference.Methods:①According to the diagnostic criteria for depression in the "Diagnostic and Statistical Manual of Mental Disorders.Fourth Edition"(DSM-V).23 patients with first-episode depression(depression group)were selected and matched with gender,age,education level,BMI.etc.Methods 31 healthy control individuals were recruited(control group).②The 24-item version of the Hamilton Depression Scale(HAMD-24)was used for clinical evaluation of the two groups of subjects,and the depression in the two groups was collected according to the requirements of the"National Clinical Laboratory Procedures"(3rd Edition)in the morning after the clinical evaluation Fresh feces of patients with disease and healthy people were quickly frozen and stored in a-80℃ environment.Then DNA was extracted from the two groups of fecal samples,and the V4-V5 region of 16S rRNA gene was sequenced.③Assignment of sequenced gene sequences to operational taxonomic units(OTOs)at 97%threshold,and calculate the relative abundance of bacterial communities at different levels.Afterwards,the tested intestinal flora is tested for a diversity(metrics include chao index,shannon index,simpson index,coverage index),β diversity test,significant test of difference between groups,correlation test between intestinal flora and depressive symptoms,significance test of difference uses student t test,correlation test uses person correlation test,setp<0.05 is statistically significant.Results:①There was no significant difference between first-episode depression patients and healthy people(α diversity test and β diversity test showed no significant difference,p>0.05).②The composition of the gut microbial structure of patients with depression has changed.At the phylum level,the abundance of the Bacteroidota differs significantly between the two groups(p=0.04).at the class level,Bacreroidiahad significant difference in the relative abundance of the two groups(p=0.04);at the order level,Bacillales,Acidaminococcales,Bacteroidales and Clostridias(p=0.00,p=0.04,p=0.04,p=0.04)had a significant difference.At the family level,there were significant differences between the two groups in Bacillaceas,Sutterellaceae,Oscillospiraceae and Acidaminococcaceae(p=0.00,p=0.00,p=0.02,p=0.04).At the genus level and species level,the abundances of 28 genera and 40 species were significantly different between the two groups.This study lists the top ten bacterial genera/species in average abundance.③In the correlation test of the intestinal flora abundance and depressive symptoms in the depression group,the HAMDS score,Shannon index,and Chao index were significantly correlated(p<0.05),and the Simpson index was not significantly correlated with other indicators(p>0.05);different levels in the depression group in the correlation test of the relative abundance of the following bacterial groups and depressive symptoms;at the phylum level,therelative abundance of Desulfobacterota and depressive symptoms were significantly correlated(r=0.4,p=0.04);at the class level,there were there lative abundance of Coriobacteriiaand,Desulfovibrionia had significantly correlated with depressive symptoms(r=0.68,p=0.00;r=0.4,p=0.04);at the order level,the Corriebacteriales and Desulfovibrioles are associated with depressive symptoms(r=0.68,p=0.00;r=0.4,p=0.04);at the family level,the Coriobacteriaceae,Eggerthellaceae,Coriobacteriales_Incertae_Sedis,Corynebacteriaceae,Desulfovibrioceae are associated with depressive symptoms(r=0.52,p=0.02;r=0.51,p=0.03;r=0.49,p=0.04;r=0.50,p=0.03;r=0.47,p=0.04);at the genus level Among them,Collinsella,Desulfovibrio,Adlercreutzia,CAG-352 had significant correlations with depressive symptoms(r=0.52,p=0.00;r=0.55,p=0.01;r=0.53,p=0.02;r=0.50,p=0.03);at the species level,Collinsella_aerofaciens,uncultured_bacterium_g_Adlercreutzi,s_uncultured_g_CAG-352 are significantly correlated with depressive symptoms(r=0.56,p=0.01;r=0.54,p=0.02;r=0.50,p=0.03).Conclusion:①In this study,no significant difference was found in the gut microbial diversity between first-episode depression patients and healthy people ②The composition of the gut microbial structure of first-episode depression patients has changed compared with that of normal people,which is mainly reflected in the significant increase in the relative abundance of Bacteroides and Blautia in the gut of depression patients.③Part of the flora at different levels is significantly related to depressive symptoms.