What is already known
Schizophrenia is a mental condition characterized by distortions in thinking, perception and behavior, affecting about 1 to 2% of the world’s population. Gut microbes are known to affect the brain through the gut-brain axis, but it is still unclear whether and how they are connected to schizophrenia.
What this research adds
Researchers analyzed stool samples from people with schizophrenia and found that they had reduced microbial diversity in their guts compared to people without the condition. Among the microbiota changes, the team found an increase in Lactobacillus species and a decrease in Bacteroides in people with schizophrenia. People with more severe symptoms showed more pronounced alterations in their gut microbiota than those with milder symptoms. For example, higher levels of Lactobacillus were linked to more severe cognitive and emotional difficulties.
Conclusions
The findings may open up new avenues for exploring interventions such as probiotics, prebiotics and dietary modifications that could restore a healthy gut microbiota and alleviate some of the symptoms of schizophrenia.
Schizophrenia is a mental condition characterized by distortions in thinking, perception and behavior, affecting about 1 to 2% of the world’s population. New research has now uncovered differences in the gut microbiota composition between people with the condition and those without.
The findings, published in PLOS ONE, may open up new avenues for exploring interventions such as probiotics, prebiotics and dietary modifications that could restore a healthy gut microbiota and alleviate some of the symptoms of schizophrenia.
Scientists have known that gut microbes can affect the brain through the gut-brain axis. For example, Clostridium coccoides has been linked with worsened schizophrenia symptoms, and bacterial infections trigger an inflammatory response in the gut, releasing inflammatory substances into the bloodstream that can influence brain function. However, it is still unclear whether and how gut microbes are connected to schizophrenia.
To explore this link, researchers led by YiMeng Wang at Inner Mongolia Medical University in Hohhot, China, analyzed stool samples from 29 people with schizophrenia and 30 people without the condition.
Microbiota profiles
The most abundant microbes in the guts of people with schizophrenia are Clostridia, Bacteroidia, Coriobacteriia, Gammaproteobacteria, Actinobacteria, Erysipelotrichia, Bacilli, Betaproteobacteria, Deltaproteobacteria and Verrucomicrobiae, the researchers found.
The team also discovered differences in the diversity and composition of gut microbiota between people with schizophrenia and those without. In particular, individuals with the condition had a decreased microbial diversity in their guts — a trait that has been associated with various diseases.
Among the microbiota changes, the researchers found an increase in Lactobacillus species and a decrease in Bacteroides in people with schizophrenia.
Clinical symptoms
People with more severe schizophrenia symptoms showed more pronounced alterations in their gut microbiota than those with milder symptoms. For example, higher levels of Lactobacillus were linked to more severe cognitive and emotional difficulties.
The team hypothesized that gut microbes might affect the brain and contribute to schizophrenia by producing neuroactive substances, modulating the immune system and influencing gut permeability — all of which can influence brain function.
“The bacterial taxa identified in this study may be important in the etiology and progression of schizophrenia,” the researchers say. However, they add, the findings should be confirmed by bigger studies. “Investigations with larger number of participants are needed to obtain further insights concerning the effects of the gut microbiota on schizophrenia.”
