By Aila Berrigan
Figure 1. Infographic about social anxiety. Graphic from zoelife, 2024.
Introduction:
Ever wonder how much of an impact your gut microbiome really makes on everyday life? New research suggests your microbiome can affect your physical and emotional well being, including levels of social anxiety. “The gut microbiota shows compositional alterations in a variety of psychiatric disorders including depression, generalized anxiety disorder (GAD), autism spectrum disorder (ASD) and schizophrenia but studies investigating the gut microbiome in social anxiety disorder (SAD) are very limited” (Butler, 2023).Therefore researchers took it upon themselves to study the effects of our microbiome on social anxiety disorder. Social anxiety disorder has become one of the most common psychiatric conditions with rates as high as 13% (Butler, 2023). The current treatments for SAD are not always effective, “the use of psychosocial/psychotherapeutic approaches declines gradually from initiation of treatment over the course of 8 years” (Keller, 2003). This has encouraged researchers to look at alternative treatments which ultimately led them to dive deeper into our gut-brain axis. “It is broadly recognized that the gut and brain are in constant bidirectional communication, of which gut microbiota and its metabolic production are a major component, and form the so-called gut microbiome–brain axis” (Sasso, 2023). With this information they hope to be able to predict and treat SAD through understanding the microbes at play.
Figure 2. Infographic showing the microbiome-gut-brain axis. Graphical abstract from Sasso, 2020.
SAD has become one of the most common psychiatric conditions with rates increasing globally (Keller, 2003). The disorder is associated with symptoms of marked fear or anxiety about one or more social situations where an individual is exposed to possible scrutiny by others. SAD can be a chronic disorder that reduces the quality of life drastically. This disorder is diagnosed through trained professionals in psychology and can be treated with medication. “Current first-line treatments include selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs) and cognitive behavioral therapy. Unfortunately, a significant proportion of patients fail to adequately respond to first-line pharmacotherapy” (Butler, 2023). With the limited success of current first line treatments researchers look to examine the microbiome-gut-brain (MGB) axis for answers.
The human microbiome is uniquely different from individual to individual. Microbes are everywhere including inside us, trillions of microorganisms colonizing our body is what makes up our microbiome and the microbes living specifically in our gut make up our gut microbiome (Sasso, 2023). These microorganisms are predominantly bacteria but can be viruses, protozoa, fungi and archaea. The gut microbiome in particular can exceed over 100 times the amount of the human genome in the body (Sasso, 2023). This gives the gut microbiome a huge genetic potential which no doubt can affect our daily processes. Since the push to discover more about gut microbiome, scientists have been able to link it to many health concerns including autoimmune, metabolic and neurological conditions. This includes everyday health concerns like allergies, celiac disease or anxiety can be linked to the composition of our gut microbiome. With how much genetic potential the gut microbiome can possess, it’s an understandable conclusion to predict that it could also play a role in social anxiety disorder.
Central Question:
Scientist (Butler, 2023), researching “The gut microbiome in social anxiety disorder: evidence of altered composition and function” analyzed the genetic makeup of fecal samples for compositional and functional differences in the gut microbiome of patients with SAD in comparison to health patients to determine whether the gut microbiome is a factor in SAD. Their main goal was to answer: does the gut microbiome really play a role in SAD?
Evidence:
This question was researched through patients who had obtained a clinical diagnosis of SAD and were between the ages of 18-65 years old. Only patients who were not taking any medication that could interfere or didn’t have acute or chronic medical illness were included. Patients taking psychiatric medications that were not predicted to influence the outcome were able to maintain that protocol. Scientists then kept track of their food frequency and intake through a questionnaire, the stool consistency, exercise levels and sleep. Fecal samples were collected from the participants and the genetic data of the microbes were processed. The study used 31 patients with SAD and 18 healthy patients as controls.
For the first time this study found that the gut microbiome is genetically different in people with social anxiety disorder (SAD) than that of healthy people. “Beta diversity, an indicator of overall microbiota composition, was significantly different between the two groups. The relative abundance of three genera, Anaeromassilibacillus, Gordonibacter and Parasutterella, and two corresponding species, Anaeromassilibacillus sp An250 and Parasutterella excrementihominis differed significantly between SAD patients and controls” (Butler, 2023). This adds to growing evidence that our social brain function and microbiome may be linked. The change in genus of the gut microbiome was significantly different between the two groups. Anaeromassilibacillus so An250 which was found in almost half the SAD patients but only one of the healthy controls. This genus is newly discovered and is also found increased in the gut of patients with autism spectrum disorder, depression and schizophrenia. This bacteria is part of the Clostridiales taxa which is a group of bacteria, the increase in Clostridiales seem to be associated with psychiatric disorder showing there may be a link to social behavior. Anaeromassilibacillus is a new addition to the human microbiome database so there is still limited research on how it affects human health.
It is hard to determine how important the difference in specific bacteria in the patient group is. This is because our gut microbiome is constantly interacting with one another and the host. Much more research is needed to fully characterize the microbial community structures and gain insights into how they influence the human host, however this study demonstrated a clear difference in microbial composition between the healthy patients and those suffering from social anxiety disorder. However a link in gut microbiome and the microbiome-gut-brain axis is yet to be fully understood.
Figure 3. Genus-level differences in relative abundance between SAD and controls seen in three genera; Anaeromassillibacillus and Gordonibacter are enriched in SAD while Parasutterella is enriched in healthy controls. B Species-level differences in relative abundance between SAD and controls; Anaeromassilibacillus sp An250 is increased in SAD while Parasuterella excrementihominis is enriched in healthy controls. (*p = <0.05) (Clr centred log-ratio transformed, HC Healthy Control, SAD Social Anxiety Disorder). Data figure from Butler, 2023.
My Questions:
More research is certainly needed to fully understand how the microbiome-gut-brain axis is influenced and what specific bacteria play the biggest roles. My question is wether or not psychotropic medication impact the gut microbiome. I would like to see this further studied to determine if there was a link between the psychotropic medications and microbiome some of the patients were taking to see if that can also explain the difference in gut microbiome composition.
Further reading:
To read the initial scientific research article that looked at the effects of the human microbiome of social anxiety disorder check the link below.
The gut microbiome in social anxiety disorder: evidence of altered composition and function
Read the article below to learn more about social anxiety disorder, including its history and how it’s diagnosed as well as treatments and symptoms.
The lifelong course of social anxiety disorder: a clinical perspective
Read the article below to learn more about the gut microbiome. This article explains how gut microbiomes are analyzed and the importance of doing so.
Read the article below to learn more about the microbiome-gut-brain axis. This article explains how it works and the value of researching the interactions between our gut microbiome and brain.
Read the article below to learn more about how the gut microbiome can play a role in other mental disorders, not just social anxiety.
References:
Butler, M. M., Bastiaanssen, T. F. S., Long-Smith, C., et al. (2023). The gut microbiome in social anxiety disorder: Evidence of altered composition and function. Translational Psychiatry, 13, 95. https://doi.org/10.1038/s41398-023-02325-5
Keller, M. B. (2003). The lifelong course of social anxiety disorder: A clinical perspective. Acta Psychiatrica Scandinavica, 108(s417), 85–94. https://doi.org/10.1034/j.1600-0447.108.s417.6.x
Sasso, J. M., Ammar, R. M., Tenchov, R., Lemmel, S., Kelber, O., Grieswelle, M., & Zhou, Q. A. (2023). Gut microbiome-brain alliance: A landscape view into mental and gastrointestinal health and disorders. ACS Chemical Neuroscience, 14(10), 1717–1763. https://doi.org/10.1021/acschemneuro.3c00127
Xiong, R. G., Li, J., Cheng, J., Zhou, D. D., Wu, S. X., Huang, S. Y., Saimaiti, A., Yang, Z. J., Gan, R. Y., & Li, H. B. (2023). The role of gut microbiota in anxiety, depression, and other mental disorders as well as the protective effects of dietary components. Nutrients, 15(14), 3258. https://doi.org/10.3390/nu15143258
Zhou, X., Shen, X., Johnson, J. S., Spakowicz, D. J., Agnello, M., Zhou, W., Avina, M., Honkala, A., Chleilat, F., Chen, S. J., Cha, K., Leopold, S., Zhu, C., Chen, L., Lyu, L., Hornburg, D., Wu, S., Zhang, X., Jiang, C., Jiang, L., … Snyder, M. P. (2024). Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease. Cell Host & Microbe, 32(4), 506–526.e9. https://doi.org/10.1016/j.chom.2024.02.012
Social Anxiety Disorder Symptoms: Signs, Effects, and Coping Strategies – ZOELIFE PSYCHIATRIC HEALTH. (2024). Retrieved from https://zoelifepsychiatricservices.com/social-anxiety-disorder-symptoms/
