The change of gut microbiota in MDD patients under SSRIs treatment

Abstract

The alterations in the gut microbiota have been reported to be correlated with the development of depression. The purpose of this study was to investigate the changes of intestinal microbiota in depressed patients after antidepressant treatment. We recruited 30 MDD patients (MDD group) and 30 healthy controls (control group). The MDD group received individualized treatment with escitalopram at a maximum dose of 20 mg/day. After depressive symptoms improved to a HAMD scale score > 50%, a fecal sample was collected again and used as the follow-up group. The differences of gut microbiota between patients and controls, the characteristics of gut microbiota under treatment and the potential differences in metabolic functions were thus investigated. The Firmicutes/Bacteroidetes ratio was significantly different within three groups, and the ratio of follow-up group was significantly lower than those of the other two groups. Alpha diversity was significantly higher in MDD group than those of the other groups, and the alpha diversity was not significantly different between control and follow-up groups. The beta diversity of some patients resembled participants in the control group. The metabolic function of gut microbiota after treatment was still different from that of the control group. This study suggests that the intestinal flora of depressed patients has a tendency to return to normal under escitalopram treatment.

A systematic review of gut microbiota composition in observational studies of major depressive disorder, bipolar disorder and schizophrenia

“…Four studies included subgroups of the data. Subgroups included participants either aged 18–29 years or 30–59 years [ 69 ], males or females [ 70 ], active MDD cases or those considered in remission (R-MDD) [ 73 ] and MDD patients at baseline then after antidepressant treatment [ 89 ]. Results for these subgroups were extracted separately and compared to their control group.…”

“…Another study observed correlations between specific bacterial taxa and functional pathways within the KEGG orthologue database; however, they did not report what the specific pathways were, only providing the KEGG identification number [ 88 ]. Of the studies that examined multiple pathways and reported differences ( N = 9), MDD was associated with an enrichment of: glycan biosynthesis and metabolism (33%; N = 3/9 reported studies) [ 86 , 89 ]; lipopolysaccharide biosynthesis and biosynthesis proteins (33%; N = 3/9 reported studies) [ 72 , 85 ]; and transport and catabolism pathways (33%; N = 3/9 reported studies) [ 86 , 89 ], compared to controls. Conversely, cell motility and secretion (33%; N = 3/9 reported studies) [ 71 , 89 ] and membrane transport (33%; N = 3/9 reported studies) [ 86 , 89 ] were pathways enriched in controls compared to cases.…”

“…Of the studies that examined multiple pathways and reported differences ( N = 9), MDD was associated with an enrichment of: glycan biosynthesis and metabolism (33%; N = 3/9 reported studies) [ 86 , 89 ]; lipopolysaccharide biosynthesis and biosynthesis proteins (33%; N = 3/9 reported studies) [ 72 , 85 ]; and transport and catabolism pathways (33%; N = 3/9 reported studies) [ 86 , 89 ], compared to controls. Conversely, cell motility and secretion (33%; N = 3/9 reported studies) [ 71 , 89 ] and membrane transport (33%; N = 3/9 reported studies) [ 86 , 89 ] were pathways enriched in controls compared to cases. One study did not observe any differences between MDD cases and controls across multiple investigated pathways [ 81 ].…”

“…Six studies with repeated measurements (follow-up) data observed changes in gut microbiota composition associated with treatment. Three studies were conducted in MDD: one study collected data at three time points across 30 days of escitalopram treatment [ 76 ] and did not observe clustering of MDD cases based on visit number using PCoA of weighted UniFrac distances, however they did observe changes in bacterial taxa across the three time points suggesting compositional changes associated with treatment; one study reported changes in gut microbiota composition after individualised treatment with escitalopram (maximum dose 20 milligrams per day) and found that gut microbiota composition was more similar to controls after treatment [ 89 ]; and the third study observed changes in gut microbiota composition after 4-weeks and 8-weeks of treatment with vortioxetine hydrobromide and observed a attenuation of the differences in α-diversity between cases and controls associated with treatment, and changes in the relative abundance of specific taxa after treatment [ 90 ]. One study, in BD, observed differences in the enrichment of specific bacterial taxa associated with 4-weeks of quetiapine treatment [ 95 ].…”

“…The major sources of potential bias were lack of adequately specified and defined study populations, poor reporting of recruitment details and inclusion and exclusion criteria consistency, and lack of consideration of the pre-specified key potential confounding variables (Table S9 ). Only eight studies (18%) were categorised as ‘Good’ [ 73 , 77 , 86 , 89 , 90 , 95 , 106 , 111 ], and only two studies (5%) clearly considered all of the key potential confounding variables [ 86 , 106 ].…”