Irritable Bowel Syndrome and Mental Health- What’s the Connection?

“All disease begins in the gut” - Hippocrates

Irritable Bowel Syndrome (IBS) like most “syndromes” in western medicine, is a term to group certain symptoms together for a process that is usually diagnosed by excluding other possibilities.  A “diagnosis of exclusion” simply means there is not a definitive test for the syndrome or any other physical explanation for the symptoms someone is experiencing. 

IBS is classified into four types (usually- although there is ongoing research and discussion about these subtypes): diarrhea predominate, constipation predominant, mixed constipation and diarrhea, and post-infectious IBS. 

IBS is sometimes referred to as a “functional” syndrome; when something in medicine is referred to as “functional” it means there are no physical abnormalities observable by the medical provider and the symptoms described by the person is what helps ultimately decide on a diagnosis.

Inflammatory Bowel Disease (IBD) is a disease process with a known cause.  For example, ulcerative colitis and Crohn’s Disease are two IBDs.  There are tests that definitively confirm these disease processes. 

Depression is a mental health disorder characterized by decreased interest or pleasure in activities, feeling down, depressed, or hopeless, feeling tired or having decreased energy.  Depression can also make it difficult to concentrate, cause you to feel bad about yourself, and affect sleeping patterns either by making sleep difficult or sleeping too much.

Anxiety can be normal in certain situations, but becomes a mental health disorder when worries, fears, and anxiety are strong enough to interfere with your daily life and activities.  Anxiety disorders can cause intrusive thoughts, difficulty concentrating, difficulty sleeping, fatigue, and emotional distress severe enough to cause panic attacks.

Numerous studies have linked IBS with depression and/or anxiety.  

Studies vary in the prevalence of depression/anxiety and individuals with IBS.  One meta-analysis (a study that looks at data from lots of other studies) showed patients with IBS experience depression at a rate of 38% and anxiety at a rate of 40% (BMC Gastroenterol, 2021).

Another study which followed patients after diagnosis found that even if someone had never had mental health issues before diagnosis they were more likely to develop them after diagnosis (PLoS ONE, 2015). 

Studies have also confirmed that IBS symptoms are often worsened during stressful events and receiving mental health treatment for anxiety or depression has a positive effect on the IBS symptoms (Clujul Med, 2015).

Unfortunately, no study has definitively explained the “why” of increased depression/anxiety in people with IBS.  

There are many theories and the predominate one is because of the “gut-brain axis” where the bowels are affected by certain neurochemicals, e.g. serotonin and norepinephrine, in more ways than are understood. And when there is gastrointestinal malfunction it can also affect the way the brain uses these same chemicals which are important in regulating mood and stress levels.

All this information indicates that mental health screening and appropriate treatment, including medication and therapy if needed, should be part of routine care for IBS patients as mental health factors are important in managing symptom longevity, severity, and if a patient seeks treatment and responds to treatment.

I will discuss more regarding treatments for IBS with coexisting depression and/or anxiety in my next article.