Anxiety and Constipation - Causes, Symptoms & Gut-Brain Link
Lifestyle factors such as stress and anxiety disorders may be responsible for the onset of constipation, and studies show high rates in people with anxiety. Other causes of constipation include:
- Lack of fiber or fluid in the diet.
- Neurological conditions such as Parkinson’s disease or multiple sclerosis.
- An underactive thyroid (hypothyroidism).
- Lack of exercise.
- Irritable bowel syndrome.(3)
Anxiety and constipation
Anxiety is a feeling of unease or worry, and has high comorbidity (co-occurrence) with constipation. Anxiety is the primary symptom in anxiety disorders such as generalized anxiety disorder (GAD). The rate of anxiety has been shown to be over 30% in people with constipation, compared to 19% in the general population.(4),(5)
What is the link?
Science has shown a strong associative link between mental disorders and constipation. However, a causal link has not been confirmed. Studies show a slower rate of motility (speed of transit of food) through the colon in patients who have anxiety. But it is not known if anxiety appears first and causes constipation or vice-versa. Several theories have been put forward to explain the link and these involve problems in the enteric nervous system and gut-brain axis.(6)
The enteric nervous system
The enteric nervous system (ENS) or ‘second brain’ describes the nerves lining the digestive tract. These nerves consist of hundreds of millions of neurons and control the digestion of food. They also send signals from the gut to the brain. It is thought that in states of anxiety, disruption to the ENS-brain connection reduces motility(speed of transit of food) through the gastrointestinal tract, leading to constipation. This represents a malfunctioning of the ‘gut-brain axis’, which connects the gut to the brain.(7)
The gut-brain axis
The gut-brain axis is a two-way connection between the gut (and ENS), and the central nervous system (brain and spinal cord). It consists of several components:
- The sympathetic nervous system. This system releases adrenaline and other hormones from the brain and glands of the body, stimulating the ‘fight or flight’ response to influence the transit of food through the gut.
- The hypothalamic-pituitary-adrenal (HPA) axis. This system secretes cortisol in the stress response and is affected by microbes in the digestive tract.
- Immune signaling. Specialized cells in the immune system can modify the activity of sensory neurons in the gut and affects digestion.
- Gut bacteria. Bacteria in the digestive tract produce neurotransmitters such as serotonin, which influence the activity of the nervous system.(8),(9)
Disruptions in these systems of the gut-brain axis occur in anxiety, and this may cause constipation. For example, anxiety may act to restrict the function of smooth muscle to cause constipation. Alternatively, stresses not coped well may be ‘internalized’ and lead to changes in gut-brain signaling. These examples show how stress and anxiety reduce the transit of food through the digestive system, and cause constipation. Problems with the gut-brain axis may also be linked with irritable bowel syndrome (IBS).10
Do I have Irritable Bowel Syndrome?
If constipation is accompanied by abdominal pain, a person may have irritable bowel syndrome (IBS). Unlike ulcerative colitis that has a physical cause, this is a 'functional' gastrointestinal disorder that affects 15% of people worldwide and causes a variety of symptoms. The most common symptoms of IBS are:
- Abdominal pain
- Changes in bowel habits
- Bloating and gas(11)
For diagnosis of IBS, abdominal pain must be accompanied by at least two of the following features: improvement of symptoms with defecation, change in stool frequency, or change in stool appearance. Diagnosis with IBS may assist in treatment since anxiety is a common trigger of IBS.(12)
IBS and Anxiety
IBS is strongly linked with psychiatric disorders, including anxiety disorders. It is speculated that anxiety may worsen symptoms of IBS by:
- Increasing sensitivity of somatic (bodily) sensations
- Altering psychological perceptions of pain
- Enhancing stress and cortisol levels that influence the ENS
- Disrupting immune function(13)
Although the mechanisms for these effects still being identified, they may arise through complex interactions described by the biopsychosocial model. The model suggests a connection between human biology, social interaction, and physiology. It explains how environmental factors such as stress and anxiety may cause physical effects on the gastrointestinal system.(14)
Sub types of irritable bowel syndrome
There are four sub types of IBS, classified based on stool consistency:
- IBS with constipation (IBS-C)
- IBS with diarrhea (IBS-D)
- IBS mixed type (IBS-M)
- IBS unsubtyped (IBS-U)
IBS with constipation (IBS-C) is the most common and accounts for approximately 60% of patients. IBS-D is the least common and comprises 5% of patients.(15)
Treatment of IBS-C
If you suffer constipation and have been diagnosed with irritable bowel syndrome, you may suffer from IBS-C. Fortunately, there are several treatment options for patients with this condition. Many of these target not only the GI symptoms but symptoms of anxiety too. Treatments include:
- Gut-directed hypnotherapy. This involves targeting IBS symptoms to promote normal digestive function. It is effective for all subtypes.
- The low FODMAP diet. This diet eliminates common ‘trigger foods’ of IBS such as fruits and vegetables containing fructose, and dairy and is effective for all subtypes.
- Cognitive-behavioral therapy. This involves challenging negative thoughts and adopting a more positive, realistic outlook. Both symptoms of IBS and anxiety may benefit.
- Antidepressants. These medications include serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) and are prescribed in low doses. SSRIs are particularly useful for constipation-predominant IBS.(16)
- Medications for IBS-C, including: Lubiprostone (Amitiza). This drug was approved in 2008 by the FDA and increases fluid secreted by the small intestine. Linaclotide (Linzess). It was approved in 2012 and spurs more frequent bowel movements. Plecanatide (Trulance). This drug was approved in 2017 and increases fluid secretion in the digestive system.(17)
Constipation in psychiatric illness.
Constipation is strongly linked with other psychiatric disorders, beyond anxiety disorder. Across-sectional study in the Netherlands studied patients with various psychiatric illnesses and found the following proportion suffered constipation:
- Schizophrenia (50%)
- Personality disorders (47%)
- Depressive disorders (41%)
- Bipolar disorder (40%)
- Dementia (35%)
- Anxiety disorders (33%)
- Alcohol-related disorders (19%)
The study showed a substantial increase in constipation in patients with psychological illness, compared to the rate of of 15% in the general population.(18)
Constipation and mental health
Constipation has been shown to worsen psychological scores of anxiety and depression. A UK study showed constipation leads to higher levels of distress in women. The women with constipation showed higher levels of depression and anxiety and social dysfunction than healthy controls.They also experience less satisfaction in intimate relationships and an altered sense of their ‘feminine’ role. It is therefore plausible that constipation may affect one’s self-image, and that this is the source of anxiety in a vicious cycle.(18)
Is Anxiety disorder causing my constipation?
If you suffer chronic constipation, consulting a doctor will help to rule out diseases that cause constipation such as:
- Diabetes Mellitus
- Parkinson’s disease
- Multiple sclerosis
Once these are ruled out, it is more likely that stress or anxiety is causing your constipation. Then, attention can be directed towards treating this form of constipation, known as functional constipation.
Functional constipation (FC), also known as chronic idiopathic constipation (CIC), is constipation that does not have a physical cause. This distinguishes it from constipation caused by diseases, such as multiple sclerosis. FC is likely to be caused by psychological or neurological factors. A personal with functional constipation may be completely healthy, yet still suffer difficulty passing bowel movements.(19)
Treatment of Functional constipation
The National Institute for Health and CareExcellence (NICE) guidelines and results of other studies indicate the following treatments are useful for functional constipation:
- Lifestyle modification. Dietary change to increase fiber in diet through fruits and vegetables, and fluid intake.
- Laxatives, including osmotic laxatives such as lactulose or stimulant laxatives such as senna and bisacodyl.
- Probiotics. Those of the Bifidobacterium and Lactobacillus genera have been shown to increase stool frequency in adults and children and are a safe option.(19)
A Word from Mindset Health
Constipation may severely impact your quality of life. There is a strong interaction between constipation and psychiatric disorders such as anxiety. At a medical center, gastrointestinal disorders such as ulcerative colitis may be ruled out through testing and diagnosis of functional constipation confirmed. Treatment for this condition will typically involve modifying lifestyle factors such as diet, and the prescription of laxatives or probiotics, or referral for cognitive behavioral therapy or hypnotherapy. These treatments are highly effective at treating constipation, and some also treat anxiety.