Irritable Bowel Syndrome Pt.1: Exploring the connection between IBS and the brain
Irritable bowel syndrome, or IBS, is a common gastrointestinal disorder that affects millions of people across the world. Traditional treatments for the uncomfortable symptoms it presents have often focused on a diet-based approach. However, increasing amounts of research reveal that the gut-brain axis plays an important part in the disorder. In the next few posts, we’ll be looking into the brain-IBS link, talking about the microbiome, and delving deep into how stress and emotions play their part.
The communication system
If you’re a long-term reader, you may recall our blog posts on the brain-gut axis, the complex structure of communication that links the ENS, or enteric nervous system with the CNS, or central nervous system. This continual two-way communication system carries a wealth of hormonal, neuronal, and immune signals. This bi-directional system means that the brain can send signals to the gut, impacting motility, microbiota, and more, and vice versa, the gut can send signals to the brain that affect cognitive function, emotions, and mood.
So why is all of this important when understanding IBS? Well, it’s possible that this communication system may be dysfunctional in those who experience the condition. Let’s explain further…
Stress and IBS
A lot of people who experience IBS notice that their symptoms are either brought on by or worsened by stress. Understanding the gut-brain connection helps us to make sense of this. When we experience stress, hormones like adrenaline and cortisol are released. These hormones can have a direct effect on the gut, altering motility and permeability and causing the hallmark symptoms of constipation or diarrhea. This can also lead to the development of something called visceral hypersensitivity, causing normal digestive processes to feel uncomfortable.
IBS and the ANS
Another way the brain ties into IBS has to do with the role of the ANS, or autonomic nervous system, and the vagus nerve. This system is responsible for a whole range of involuntary bodily functions, such as digestion.
There are actually two elements to the ANS. Firstly there is the SNS, or sympathetic nervous system, that controls our “fight or flight” function. Then there is the PNS, or parasympathetic nervous system, which is involved in our “rest and digest” response. It’s thought that in some individuals with IBS, the delicate balance between these two systems may be slightly off. For example, an SNS that is overactive can cause increased sensitivity in the gut and faster motility causing diarrhea, and a PNS that is underactive could lead to impaired digestion and constipation.