Functional stomach problems
What are "functional" stomach problems and how are they related to disorders of the brain-gut interactions?
Dyspepsia, Gastroparesis, Cyclic Vomiting Disorder, and Cannabis Hyperemesis Syndrome
Functional stomach problems involve potentially debilitating symptoms, such as pain, bloating, or motility problems, but without apparent cause. That is, there is no blockage or obvious inflammation. These disorders have traditionally been dismissed as “psychogenic”, but we now know that they are consequent problems with gut microbes, the gut immune system, and the gut nervous system- including the nerves that connect the gut to the brain. The constellation of “functional bowel disorders”, including functional stomach disorders, are now considered Disorders of Gut-Brain Interactions (Rome Foundation, 2021).
Why are they called Disorders of Gut-Brain Interactions?
In addition to troublesome stomach and intestinal symptoms, these disorders involve brain-related symptoms, such as mood problems (anxiety, depression), fatigue, cognitive “fuzziness”, and sleep disturbances. Thanks to the close connections between the gut and brain, what happens in the gut affects the brain and vice versa.
Functional dyspepsia
Functional dyspepsia is a cluster of syndromes that involve a burning sensation or pain, feeling excessively “full” after a meal or having early satiety, stomach bloating, or delayed emptying (Stanghellini 2017). People with these symptoms should first be tested for Helicobacter pylori infection. If the test is negative and there is no other observable explanation (such as a blockage or ulcer), the diagnosis is functional dyspepsia.
One syndrome called post-prandial distress syndrome (pain or bloating after a meal) is similar to irritable bowel syndrome (IBS) and may follow from motility problems (stomach emptying slowly).
Another syndrome, epigastric pain syndrome, involves pain and burning in the stomach region that may be similar to heartburn or peptic ulcer (Ford 2020). One interesting thing about epigastric pain syndrome is that the pain may not necessarily be associated with meals. In fact, pain may even be lessened by eating.
Gut Advice
Like the other Functional Bowel Disorders/Disorders of Gut-brain Interaction, the causes and contributing factors are multifactorial (Stanghellini 2017) and not completely understood. This means that practitioners must be clear that the lack of obvious cause does not mean there IS no cause, and patients need to be patient! Each case is distinctive and may take time to develop the multifactorial treatment plan that functional disorders require.
All disorders of Brain-Gut Interactions are sensitive to psychological stress, and psychological stress can enhance pain via visceral hypersensitivity (Skrobisz 2019). Visceral hypersensitivity is when the pain neurons that innervate the gut become sensitized and dysregulated, reducing their thresholds to signaling pain (Creekmore 2018, Vermeulin 2014). For these reasons, it is essential to address potential stressors. Cognitive behavioral therapy has been shown to be helpful for functional gut disorders (Angus-Leppan 2018), as have relaxation-based mind-body therapies (Shah 2020).
Gastroparesis
Gastroparesis is a condition in which, like functional dyspepsia, the stomach empties very slowly. This is usually accompanied by nausea, vomiting, or early satiety. Although gastroparesis has features similar to dyspepsia, it is not actually classified as a Disorder of Gut Brain Interaction. This is because it results from known causes, such as neuropathy. This condition is generally associated with the loss of gut neurons and non-neuronal cells that mediate motility (Grover 2019). Gastroparesis is more common in women, especially those who are overweight or obese (Grover 2019).
The most common cause of gastroparesis is diabetes (Sendzischew Shane 2021). Diabetes can damage the vagus nerve (neuropathy), which controls gastric emptying, by opening the sphincter (pylorus) that separates the stomach from the small intestine. Diabetes also damages the special cells, called the interstitial cells of Cajal, that are responsible for initiating stomach contraction. When they are damaged, the stomach cannot empty properly.
Gastroparesis associated with diabetes may also be caused by persistent hyperglycemia. In the normal course of a meal, hyperglycemia signals that food is being absorbed and slows down gastric emptying, presumably allowing food already in the small intestine to be absorbed before more arrives. Thus, this may contribute to gastric emptying (gastroparesis) delays seen in diabetic patients.
Damage to the vagus nerve can also happen during surgical interventions, such as bariatric surgery, which like damage to the vagus from diabetes can also lead to gastroparesis. (Camilleri 2018).
Finally, gastroparesis can also occur secondary to other conditions, especially progressive neurological disorders, such as neuromuscular disorders. These may impair the muscles in the gut from moving food. Neurodegenerative disorders, especially Parkinson’s Disease, can also impair motor function (Sendzischew Shane 2021).
Gut Advice
Certain medications can cause or worsen symptoms of gastroparesis (Sendzischew Shane 2021), including proton pump inhibitors and anti-diabetes medications (GLP receptor agonists). It is essential to be aware of any possible drug-related contributions to symptoms, particularly in older people who may be taking several different medications.
Avoid taking opiate medications. Because gastroparesis can be painful, some patients are prescribed opiates. They should be avoided, however, because opiates by themselves slow gastric emptying, worsening the problem. Studies have shown that people with gastroparesis who take opiates have more complications and worse prognosis than patients who do not take opiates (Camilleri 2018).
Changing diet and eating behavior is key to managing gastroparesis (Camilleri 2018). It is best to limit fats in the diet, as they tend to slow stomach emptying. Eating smaller meals more frequently can help, as can including liquid food, such as soups, in the diet.
If gastroparesis is associated with diabetes, it is important to get glucose levels under control, but some medications may exacerbate gastroparesis. Thus, sticking to a diet that contains fruits, vegetables, and fiber (such as beans) and avoiding refined carbohydrates and sodas may be the most effective way to do that. If more liquid food is easier to tolerate, an immersion blender can turn these ingredients into a quick soup.
Because stress can have deleterious effects on gut function as well impair efforts to control eating, stress management approaches that are helpful for dyspepsia can be helpful for gastroparesis as well.
Cyclic vomiting disorder
This disorder involves episodes of severe nausea, vomiting, and pain that can last up to a week, separated by periods of normal health. It seems to be more common in children and teenagers, but it also affects adults (Kovacic 2018, Raucci 2020). About 60% of children “outgrow” the condition (Raucci 2020). Although it is less common than other functional bowel disorders (affecting about 2% of the US population), cyclic vomiting disorder is the most dangerous (Kovacic 2018). Patients often require intravenous fluids during episodes and can require hospitalization. Children typically miss weeks of school per year, and some adults cannot keep working.
The causes of cyclic vomiting disorder are still mysterious, but it shares common features with migraine headaches (Kovacic 2018). Indeed, many people with cyclic vomiting disorder go on to develop migraines, and migraine medication can be helpful for some patients. People with cyclic vomiting disorder may also suffer abdominal migraines (Lenglar 2021), a pain condition involving the gut.
Persistent nausea and vomiting point to autonomic dysfunction (vagal/sympathetic imbalance) that may originate in the brain (Kovacic 2018, Raucci 2020). The brainstem and vagus nerve are key to vomiting behavior, which usually occurs when the immune and/or the nervous system detects the presence of toxins. This system is broadly part of the brain’s challenge-response/stress system, by which environmental situations (such as stress) trigger bodily responses to that situation. Cyclic vomiting disorder runs in families, and the underlying factors seem to associate with neuronal hyperexcitability and mitochondrial dysfunction. One hypothesis is that stress leads to the activation of autonomic neurons that mediate vomiting and that these neurons are hyperexcitable, leading to persistent vomiting (Raucci 2020).
Gut advice
Consistent with other functional bowel disorders/disorders of gut-brain interaction, people with cyclic vomiting disorder experience sickness syndrome symptoms, especially anxiety, fatigue, and depression. Similarly, because psychological stress seems to contribute to the onset of episodes (Kovacic 2018, Raucci 2020), learning to manage challenges and potentially stressful situations can likely help reduce the frequency of episodes.
Other lifestyle factors, including diet, physical activity, and sleep also contribute to the risk of CVS. Because poor diets can lead to disturbances in gut microbe populations, which can activate the vagus nerve, being sure to eat a diet rich in fiber, fruits and vegetables is essential. Sugary processed foods and other “junk foods” should be avoided. This can be a challenge for many children, who can be “picky eaters”. One way to get children to be more interested in healthy foods is to get them involved in preparing meals while discussing what foods make a healthy meal. Another way is by getting into gardening. Growing berries and vegetables can be an effective way to get kids to eat them (DeCosta 2017).
Cannabis hyperemesis syndrome (CHS)
CHS is a recent diagnostic category seen in chronic cannabis users that shares many features with cyclic vomiting disorder. It may, in fact, be a subcategory. Little is known about CHS, including how common it is (Kovacic 2018, Venkatesan 2019). One study reported that CHS was very rare. Still, another study reporting on people using cannabis who came to hospital emergency departments reported that about one-third of “daily or near-daily” cannabis users reported symptoms of CHS.
In some ways, CHS seems paradoxical. Cannabis can be used to prevent nausea and vomiting, for instance, in the context of cancer chemotherapy. How is it that it can actually induce nausea and vomiting? The answer seems to be related to dose, such that lower doses prevent emesis, but higher or more frequent doses induce it (Perisetti 2020). There may also be a genetic susceptibility to CHS, perhaps related to the function of the endocannabinoid system.
Gut Advice
This is a pretty new diagnosis, so there is a lack of studies reporting on long-term outcomes and interventions (Venkatesan 2019). The obvious thing to do is either reduce or abstain from cannabis use; the limited information available supports that.
Antiemetic medications, such as the serotonergic drug ondansetron (used for preventing side effects of cancer chemotherapy), are generally not effective for CHS and carry risks for serious side effects, including heart arrhythmias (Perisetti 2020).
Taking hot baths or showers seems to help relieve symptoms (Venkatesan 2019, Perisetti 2020). Indeed, “pathological hot bathing behavior” has been suggested to be a diagnostic feature of CHS. But about half of people with CVD (non-cannabis-related) also take hot baths or showers to relieve symptoms. Hot baths may function to improve autonomic balance, perhaps via effects on the hypothalamus (Perisetti 2020).
References
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