Depression And The Human Gut Microbiota

Depression is one of the most common disorders responsible for disability in humans worldwide. The causation of this reocurring condition has been found to involve the dysregulation in neuroendocrine (hormonal), neurotransmitter, and metabolic systems. Let’s take a look at how this disruptance affects the body, as we look at the depression and gut microbiota connection. 

How Are Depression and Human Gut Microbiota Connected?

Over the years, there has been enough evidence pointing towards the role of gut microbes in neural development and function. Together, the intestinal bacteria represents a virtual organ of sorts inside of us. In fact, these cells have almost 100 times more genetic material present than all the cells in our human body.

Unfortunately, the classification of all the microbes present in our body is incomplete. About 60% of these microbes cannot be grown in a lab for studies.

Even though the role of gut microbes in neurological conditions has not been well established, there has been a rapid increase in evidence which underlines the possibility that changes in the gut microbial environment have an effect on the normal functioning of our nervous system. Hence, our gut environment can have a major role to play in our mood and also in depression.

Gut Microbiota and the Brain

There exists a bidirectional communication between our gut microbiota and the components of the gut-brain axis. This communication can influence the normal functioning of the gut and may contribute to a risk of diseases in humans.

Changes in gastrointestinal (GI), autonomic nervous system (ANS), immune system, enteric (intestinal) nervous system (ENS), and central nervous system (CNS) brought about by the microbiota can lead to alterations in the following :

  • GI barrier function
  • Fat storage and energy balance
  • Increased stress reactivity
  • General low-grade inflammation (GI and systemic)
  • Depressive-like behaviors and increased anxiety

All the above-mentioned mechanisms are found to be involved in the development of mood and anxiety disorders in humans.

Gut Microbiota and Mood

The vast number of bacteria which constitute the intestinal microbiome are engaged in interactions with each other, as well as its local environment, in a balanced manner. This tight-rope act is done to achieve the normal functioning of our body.

Microbes produce a wide range of biologically and neuroactive (acting on the nervous system) molecules, complete with neurotransmitters and an extensive set of short-chain fatty acids. Short-chain fatty acid are produced through fermentation, all of which have known and unknown effects on the nervous system.

These direct and indirect effects of the intestinal microbes on the intestinal tissues, local immune system and their components, and the enteric (intestinal) nervous system, affect the neuronal pathways of our brain. The above-mentioned processes together influence our mood and cognition by acting upon the components of our neural system. Increasing evidence points to a strong relationship between our intestinal health and our mental well being.  

Depression and the Microbiome

Depression is associated with altered gut microbial composition, richness, and diversity. In a study conducted where the researchers transplanted the microbiota signature found in depressed patients to rats whose own microbiota was purposefully depleted, this procedure induced the development of some of the behavioral (anxiety, anhedonia) and physiological features of the depressive state.    

Studies have also shown the impact of early life stress in remodeling the gut microbial composition. Subtle changes in microbial acquisition and maintenance during the vulnerable early life period may contribute to the predisposition of the individual to stress-related disorders in the adulthood. This can be a result of the effect of these subtle changes in our microbiome on the neuro signalling pathways of the brain-gut microbiota axis.

There is growing evidence suggesting the role of our intestinal microbes in neural development, both centrally in the brain and in the enteric nervous system. Depression is characterized by alterations in the gut microbiota and hence, we need to understand our gut so as to ensure a healthy functioning of our bodily systems. 

Understanding the gut brain connection gives us more tools in treating depression and other disorders of the brain. By sequencing your microbiome with consumer testing like Thryve, you’ll be able to gain more insights into how each of these microbes may contribute to your mood. Probiotics have also shown in studies to reverse negative emotions and enforce positive thinking. All in all, this should be enough to give us a whole new meaning to the quote: “You are what you eat.”  

References

Disclaimer: The above article is sponsored by Thyrve, the world’s first Gut Health Program that incorporates microbiome testing and personalized probiotics to ensure a healthier gut, happier life, and a brighter future.