Gastroparesis, a condition of delayed stomach emptying without a physical blockage, is a common non-motor symptom in people with Parkinson’s disease, a progressive neurodegenerative disorder known for its effects on movement. The presence of gastroparesis can complicate Parkinson’s management and affect an individual’s quality of life.
The Neurological Link Between Parkinson’s and Gastroparesis
The development of gastroparesis in people with Parkinson’s is rooted in the disease’s impact on the autonomic nervous system. This network regulates involuntary bodily functions, including the muscular contractions that move food through the digestive tract. This dysfunction disrupts the coordinated actions required for timely stomach emptying, and the vagus nerve, which signals stomach muscles to contract, can be compromised.
Parkinson’s disease is characterized by the accumulation of a protein called alpha-synuclein into clumps known as Lewy bodies. These protein deposits are found not only in the brain but also in the enteric nervous system (ENS), the nerve network within the gastrointestinal tract. The presence of alpha-synuclein in the ENS is believed to cause nerve damage that impairs gastric motility by interfering with signals that control digestive muscle contractions.
Evidence suggests a strong gut-brain connection in Parkinson’s progression, with some research indicating alpha-synuclein pathology may spread from the gut to the brain via the vagus nerve. The dopaminergic pathways, known for their role in motor symptoms when depleted in the brain, also help regulate digestive function. Disruption of these pathways outside the central nervous system contributes to the delayed gastric emptying of gastroparesis.
Identifying Gastroparesis Symptoms in Individuals with Parkinson’s
The symptoms of gastroparesis can create daily challenges and lead to inadequate nutrition, unintentional weight loss, and dehydration. Common signs include:
- A persistent sense of nausea
- Vomiting, which may contain undigested food from hours earlier
- Abdominal pain or bloating after eating
- Early satiety, or feeling full after eating only a small amount
For those with Parkinson’s, these symptoms can be particularly troublesome. It can be difficult to distinguish them from the side effects of medications, which sometimes cause similar gastrointestinal upset. Because digestive issues are prevalent among patients, open communication with a healthcare provider about any new or worsening symptoms is necessary for a proper diagnosis.
Diagnostic Process for Gastroparesis in Parkinson’s
Diagnosing gastroparesis in a patient with Parkinson’s involves measuring the speed of stomach emptying and excluding other causes. The most common method is gastric emptying scintigraphy. For this test, the patient consumes a light meal, like eggs or oatmeal, containing a small amount of a radioactive substance.
A special camera tracks the radioactive tracer as it moves through the stomach. Images are taken at intervals over about four hours to measure the emptying rate. If a significant amount of the meal remains in the stomach after this period, it confirms a diagnosis of delayed gastric emptying.
A physician will also work to rule out any physical obstruction in the stomach or small intestine that could be causing the delay. This is often done with an upper endoscopy, where a thin, flexible tube with a camera is passed down the throat to visually inspect the esophagus, stomach, and the beginning of the small intestine. Other diagnostic tools, like a wireless motility capsule or breath tests, may also be used.
Therapeutic Approaches for Gastroparesis in the Context of Parkinson’s
A foundational strategy for managing gastroparesis involves dietary modifications. Patients are advised to eat smaller, more frequent meals to reduce the volume of food the stomach must process at one time. A diet low in fat and insoluble fiber is also beneficial, as these components slow digestion, while pureed or liquid foods may be needed in severe cases to ensure adequate nutrition.
Gastroparesis affects the absorption of Parkinson’s medications. Levodopa, a primary medication for motor symptoms, is absorbed in the small intestine. When the stomach empties slowly, the drug can be trapped, leading to delayed or reduced effects and unpredictable “ON” and “OFF” periods. This can be managed by adjusting medication timing, crushing tablets, or using alternative formulations like intestinal gels or patches that bypass the stomach.
Pharmacological treatments for gastroparesis must be chosen with caution, as some can interfere with Parkinson’s treatments or worsen symptoms. Medications that promote stomach emptying, known as prokinetics, are an example. Metoclopramide is generally avoided due to its risk of causing movement-related side effects, and domperidone is not widely available in the United States. For severe, treatment-resistant gastroparesis, advanced interventions like gastric electrical stimulation may be considered.