Table 1.
Summary of studies investigating the microbiome in patients with schizophrenia.
| Publication | Study Design | Diversity Findings | Taxa Abundance Differences in Schizophrenia |
|---|---|---|---|
| He et al., 2018 [33] | Gut microbiome 81 high-risk schizophrenia patients, 19 ultra-high-risk schizophrenia patients, 69 healthy controls Recruited from the Second Xiangya Hospital, Central South University, Changsha, Hunan, China Experimental Method: 16S rRNA gene sequencing from stool samples collected at baseline |
No significant differences between the groups | Observed increased relative abundance of various taxa in schizophrenia: Orders: Bacteroidales, Clostridiales, Lactobacillales Genera: Lactobacillus, Prevotella Species: Lactobacillus ruminis |
| Castro-Nallar et al., 2015 [34] | Oral microbiome 16 schizophrenia patients, 16 healthy controls Recruited from the Stanley Research Program at Sheppard Pratt Hospital Maryland, US Experimental Method: Illumina sequencing of DNA from throat swabs |
Lower species richness and more homogenously distributed in schizophrenia patients | Observed increased relative abundance of various taxa in schizophrenia: Phyla: Firmicutes Genera: Bifidobacterium, Lactobacillus Species: Bifidobacterium pseudocatenulatum, Candida dubliniensis, Catenibacterium mitsuokai, Eubacterium hallii, Lactobacillus gasseri, Lactobacillus salivarius |
| Yolken et al., 2020 [35] | Oral microbiome 121 schizophrenia patients, 85 healthy controls Recruited from psychiatric programs affiliated with the Sheppard Pratt Health System and at other outpatient treatment sites in central Maryland, US Experimental Method: 16S rRNA gene sequencing of V3–V4 region from throat swabs |
No significant differences in alpha diversity (microbial richness and diversity) were found Altered beta diversity was found in individuals with schizophrenia compared to healthy controls |
Observed increased relative abundance of various taxa in schizophrenia: Genera: Streptococcus Observed decreased relative abundance of various taxa in schizophrenia: Families: Weeksellaceae Genera: Prevotella Species: Neisseria subflava |
| Zhang et al., 2020 [36] | Gut microbiome 10 antipsychotic-naïve patients with first-episode schizophrenia, 16 healthy controls Recruited from the Seventh People’s Hospital of Hangzhou in Hangzhou, Zhejiang Experimental Method: 16S rRNA gene sequencing from stool samples collected at baseline |
No significant differences in alpha diversity (microbial richness and diversity) were found Principle coordinate analysis distinguished a cluster between the two groups, indicating a significant decrease in beta diversity in the schizophrenia group compared to the control group |
Observed increased relative abundance of various taxa in schizophrenia: Phyla: Proteobacteria Classes: Deltaproteobacteria, Saccharimonadia, Synergistia Orders: Actinomycetales, Desulfovibrionales, Saccharimonadales, Synergistales Families: Actinomycetaceae, Burkholderiaceae, Desulfovibrionaceae, Saccharimonadaceae, Synergistaceae Genera: Actinomyces, Anaerotruncus, Bilophila, Blautia, Christensenella, Cloacibacillus, Dorea, Eggerthella, Eisenbergiella, Flavonifractor, Holdemania, Hungatella, Oscillibacter, Parasutterella, Prevotella Observed decreased relative abundance of various taxa in schizophrenia: Families: Lachnospiraceae Genera: Agathobacter, Butyricicoccus, Coprococcus, Faecalibacterium, Fusicatenibacter, Ruminococcus |
| Yuan et al., 2018 [37] | Gut microbiome 41 antipsychotic naïve patients with first-episode schizophrenia and 41 healthy controls Patients were started on risperidone treatment for 24 weeks (1–6 mg/day) Recruited from First Affiliated Hospital of Zhengzhou University Experimental Method: 16S rRNA gene sequencing from stool samples collected from baseline, weeks 6, 12 and 24 |
Not reported | Abundance of Bifidobacterium spp. and Escherichia coli increased with risperidone treatment Abundance of Lactobaccillus spp. and Clostridium coccoides decreased with risperidone treatment Observed increased relative abundance of various taxa in schizophrenia: Species: Clostridium coccoides Observed decreased relative abundance of various taxa in schizophrenia: Genera: Bifidobacterium., Lactobacillus Species: Escherichia coli |
| Zhu et al., 2020 [38] | Gut microbiome 90 antipsychotic-free patients with first-episode schizophrenia and 81 healthy controls Followed up with 38 patients after 3 months of treatment (27 risperidone and 11 other antipsychotics) Recruited from multiple clinical sites across the Shaanxi Province, China Experimental Method: Metagenomic shotgun sequencing from stool samples collected at baseline and 3 months after antipsychotic treatment |
Higher alpha diversity (microbial richness and diversity) was observed at the genus level Individuals with schizophrenia presented with a more variable gut microbiome compared to healthy controls |
Observed increased relative abundance of various Species in chronically antipsychotic-treated schizophrenia compared to: HC: Acidaminococcus fermentans, Acidaminococcus intestini, Akkermansia muciniphila, Alkaliphilus oremlandii, Bacillus amyloliquefaciens, Bacteroides plebeius, Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium dentium, Bifidobacterium longum, Enterococcus faecium, Eubacterium siraeum, Lactobacillus casei, Lactobacillus crispatus, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus oris, Lactobacillus ruminis, Lactobacillus salivarius, Methanobrevibacter smithii, Pseudoflavonifractor capillosus, Stenotrophomonas maltophilia, Streptococcus anginosus, Streptococcus mutans, Veillonella atypica, Veillonella parvula FSCZ: Actinomyces odontolyticus, Enterobacter aerogenes, Enterobacter asburiae, Enterobacter cancerogenus, Enterobacter cloacae, Escherichia coli, Lactococcus lactis, Victivallis vadensis, Observed decreased relative abundance of various Species in chronically antipsychotic-treated schizophrenia compared to: HC: Bacteroides intestinalis, Lactobacillus acidophilus, Lactococcus lactis FSCZ: Alkaliphilus oremlandii, Anaerostipes caccae, Bacteroides ovatus, Bifidobacterium angulatum, Bifidobacterium bifidum, Bifidobacterium longum, Clostridium bolteae, Dorea formicigenerans, Enterococcus faecium, Eubacterium hallii, Faecalibacterium prausnitzii, Lactobacillus ruminis, Streptococcus anginosus Observed increased relative abundance of various Genera in first-episode schizophrenia compared to controls: Acidaminococcus, Akkermansia, Anaerotruncus, Bifidobacterium, Citrobacter, Clavibacter, Comamonas, Coprobacillus, Cryptobacterium, Dialister, Enterococcus, Lactobacillus, Methanobrevibacter, Peptoniphilus, Pseudoflavonifractor, Veillonella Observed decreased relative abundance of various Genera in first-episode schizophrenia compared to controls: Butyrivibrio, Gemella |
| Pełka-Wysiecka et al., 2019 [39] | Gut microbiome 20 schizophrenia patients Patients underwent a 7 day washout and were started on olanzapine for 2 weeks (5–20 mg/day). Recruited from Department of Psychiatry in Szczecin (Poland) Experimental Method: 16S rRNA gene sequencing of V4 region from stool samples collected after washout and week 2 of treatment. |
No significant changes in alpha diversity after 2 weeks of olanzapine treatment | No significant changes in OTU abundancies between weeks 0 and 6. No changes in Firmicutes/Bacteroidetes ratio |
| Shen et al., 2018 [40] | Gut microbiome 64 schizophrenia patients on antipsychotic medication and 53 healthy controls Recruited from hospital or outpatient clinics within Huludao area in China Experimental Method: 16S rRNA gene sequencing of V3–V4 region from stool samples collected at baseline |
No significant differences in alpha diversity (microbial richness and diversity) were found |
Observed increased relative abundance of various taxa in schizophrenia: Phyla: Proteobacteria Classes: Gammaproteobacteria Orders: Aeromonadales, Fusobacteriales Families: Enterobacteriaceae, Fusobacteriaceae, Lactobacillaceae, Prevotellaceae, Succinivibrionaceae, Veillonellaceae Genera: Acidaminococcus, Citrobacter, Clostridium, Collinsella, Desulfovibrio, Fusobacterium, Klebsiella, Lactobacillus, Megasphaera, Phascolarctobacterium, Prevotella, Succinivibrio Species: Bifidobacterium adolescentis, Bacteroides fragilis, Collinsella aerofaciens, Lactobacillus mucosae, Prevotella stercorea Observed decreased relative abundance of various taxa in schizophrenia: Phyla: Firmicutes Classes: Clostridia Orders: Clostridiales Families: Alkaligenaceae, Lachnospiraceae Genera: Blautia, Coprococcus, Roseburia, Streptococcus Species: Bacteroides eggerthii, Blautia producta, Collinsella plebeius, Roseburia faecis |
| Nguyen et al., 2019 [41] | Gut microbiome 25 patients with chronic schizophrenia or schizoaffective disorder (most patients were being treated with antipsychotic medication), 25 demographically matched non-psychiatric controls Recruited as outpatients in San Diego Experimental Method: 16S rRNA gene sequencing of V4 region from stool samples collected at baseline |
No significant differences in alpha diversity (microbial richness and diversity) were found | Observed increased relative abundance of various taxa in schizophrenia: Genera: Anaerococcus, Blautia, Megasphaera,, Ruminococcus Observed decreased relative abundance of various taxa in schizophrenia: Phyla: Proteobacteria Genera: Clostridium, Haemophilus, Oscillospira, Sutterella Species: Haemophilus parainfluenzae |
| Zheng et al., 2019 [42] | Gut microbiome 63 schizophrenia patients (most patients were being treated with antipsychotic medication), 69 healthy controls Recruited from the First Affiliated Hospital of Chongqing Medical University Experimental Method: 16S rRNA gene sequencing of V3–V4 region from stool samples collected at baseline |
Lower alpha diversity (species richness and diversity) was observed in schizophrenia patients | Observed increased relative abundance of various taxa in schizophrenia: Families: Bacteroidaceae, Coriobacteriaceae, Prevotellaceae, Veillonellaceae Genera: Akkermansia, Fusobacterium, Megasphaera, Prevotella Observed decreased relative abundance of various taxa in schizophrenia: Families: Acidaminococcaceae, Enterobacteriaceae, Lachnospiraceae, Rikenellaceae, Ruminococcaceae Genera: Blautia, Citrobacter, Coprococcus, Lachnoclostridium Species: Bacteroides eggerthii, Bacteroides massiliensis, Collinsella stercoris, Haemophilus parainfluenzae |
| Ma et al., 2020 [43] | Gut microbiome 40 antipsychotic-naïve patients with first-episode schizophrenia (FSCZ), 85 chronically antipsychotic-treated schizophrenia patients, 69 healthy controls (HC) Recruited from the Second Xiangya Hospital of Central South University Experimental Method: 16S rRNA gene sequencing of V4 region from stool samples collected at baseline |
Lower alpha diversity (species richness and diversity) was observed in chronically antipsychotic-treated schizophrenia patients compared to antipsychotic-naïve patients with first-episode schizophrenia and healthy controls | Observed increased relative abundance of various taxa in chronically antipsychotic-treated schizophrenia compared to: Phyla HC: Proteobacteria Families HC: Christensenellaceae, Enterobacteriaceae, Enterococcaceae, Lactobacillaceae FSCZ: Enterococcaceae, Lactobacillaceae, Peptostreptococcaceae. Streptococcaceae, Veillonellaceae Genera HC: Escherichia, Bulleidia, Coprobacillus, Enterococcus, Lactobacillus, Shigella, Streptococcus, Trabulsiella, Veillonella FSCZ: Citrobacter, Clostridium, Enterobacter, Enterococcus, Escherichia, Fusobacterium, Lachnobacterium, Megasphaera, Lactobacillus, Ruminococcus, Shigella, Streptococcus, Sutterella, Veillonella Observed decreased relative abundance of various taxa in chronically antipsychotic-treated schizophrenia compared to: Phyla HC: Cyanobacteria FSCZ: Lentisphaerae Families HC: Pasteurellaceae, Turicibacteraceae Genera HC: Bacteroides, Parabacteroides, Turicibacter FSCZ: Lachnobacterium |
| Xu et al., 2020 [44] | Gut microbiome 44 schizophrenia patients, 44 healthy controls Recruited from Longgang Central Hospital of Shenzhen and Shenzhen Kangning Hospital in Shenzhen, China Experimental Method: 16S rRNA gene sequencing of V4 region from stool samples collected at baseline |
Lower species richness was observed in schizophrenia patients NMDS analysis at the species level resulted in distinct clusters with few overlaps between schizophrenia patients and healthy controls. The microbial dysbiosis index was significantly increased in patients with schizophrenia compared to controls. |
Observed increased relative abundance of various taxa in schizophrenia: Phyla: Actinobacteria Classes: Deltaproteobacteria Orders: Actinomycetales, Sphingomonadales Families: Sphingomonadaceae Genera: Eggerthella, Megasphaera Species: Akkermansia muciniphila, Bifidobacterium adolescentis, Clostridium perfringens, Lactobacillus gasseri, Megasphaera elsdeniis Observed decreased relative abundance of various taxa in schizophrenia: Orders: Rhodocyclales Families: Alcaligenaceae, Enterococcaceae, Leuconostocaceae, Rhodocyclaceae, Rikenellaceae Genera: Enterococcus |
Experimental Methods and Taxonomic Groups are in bold.