A chronic cough is a common non-motor symptom of Parkinson’s Disease (PD). This cough is often a secondary manifestation of underlying neurological changes, such as swallowing difficulties or altered respiratory function. Standard cough suppressants are frequently ineffective because they do not address the root cause of the irritation. Effective management requires a comprehensive, multi-faceted strategy that targets these specific physiological changes through therapeutic, pharmacological, and daily interventions.
Understanding the Source of the Cough
The primary cause of chronic coughing in PD relates to impaired function of the muscles controlling the throat and chest wall. This muscle discoordination leads to dysphagia, or difficulty swallowing. Impaired swallowing allows small amounts of saliva, food, or liquid to enter the airway, a process called aspiration, which triggers the protective cough reflex.
The cough itself may be ineffective at clearing the airway due to weakened respiratory muscles. PD affects the muscles responsible for generating the forceful exhale needed for a strong cough, making it difficult to expel aspirated material. This diminished cough strength, known as hypotussia, increases the risk of serious complications like aspiration pneumonia, a leading cause of death in the PD population.
Gastroesophageal Reflux Disease (GERD) also contributes to irritation. GERD occurs when stomach acid backs up into the esophagus and throat, irritating the lining and prompting a cough reflex. Furthermore, the pooling of excess saliva, or sialorrhea, which is frequent in PD, increases the risk of aspiration and stimulates the cough.
Therapeutic and Behavioral Interventions
Rehabilitation-focused interventions are effective because they target the underlying muscle weakness and discoordination. Speech-Language Pathologists (SLPs) deliver these behavioral therapies, teaching patients exercises to strengthen swallowing and coughing muscles to improve airway protection.
One common approach is Expiratory Muscle Strength Training (EMST), which involves breathing out forcefully against a resistance device. EMST strengthens the expiratory muscles, enhancing the force of a voluntary cough. This training increases cough airflows, which is essential for clearing the airway effectively.
Another technique is sensorimotor training for airway protection (smTAP), which focuses on improving the reflexive cough response. This therapy may use a low-dose, inhaled substance, like capsaicin, to safely stimulate the cough reflex under controlled conditions. Improving the reflex cough is important because it is the body’s automatic response when food or liquid accidentally enters the airway.
SLPs also instruct on postural and swallowing adjustments to prevent aspiration. Techniques include tucking the chin down while swallowing or altering the consistency of foods and liquids. These behavioral modifications reduce the likelihood of material entering the airway, decreasing the need to cough.
Pharmacological Management Options
Pharmacological strategies focus on managing the secondary conditions that trigger the cough, rather than suppressing the reflex. Since GERD is a frequent culprit, acid-reducing medications, such as proton pump inhibitors or H2 blockers, are often prescribed to minimize throat irritation from stomach acid.
For individuals experiencing excessive drooling or sialorrhea, medications aimed at reducing saliva production may be recommended. These typically include anticholinergic agents, but they must be used cautiously due to potential side effects in PD patients, such as confusion or cognitive changes. A neurologist should be consulted before starting or changing any medication regimen.
Mucolytics, which thin mucus, may be considered if thick secretions contribute to the cough. By making the mucus less viscous, these agents help the patient clear their throat more easily. However, common cough and cold medications containing ingredients like dextromethorphan or pseudoephedrine should be used with caution due to potential drug interactions with PD medications or increased blood pressure.
Daily Home Management Strategies
Simple, non-prescription adjustments to daily routine and environment can provide immediate relief from chronic coughing. Maintaining adequate hydration is fundamental, as drinking plenty of water keeps the throat moist and thins mucus, making it easier to swallow and clear.
Modifying the eating and drinking routine is also important. Meals should be taken slowly. High-protein meals should be timed carefully, as protein can interfere with the absorption of levodopa medication, potentially worsening motor symptoms that affect swallowing. Eating smaller, more frequent meals helps manage energy levels and reduces fatigue during mealtimes.
Environmental controls minimize irritants that exacerbate the cough reflex. Using a humidifier, especially in the bedroom, adds moisture to the air, which can soothe dry, irritated airways. Avoiding exposure to smoke, strong perfumes, or harsh chemical cleaners is also important, as these can trigger a heightened cough response.
If GERD is suspected, elevating the head of the bed by six to eight inches can prevent stomach acid from flowing back into the esophagus during sleep. This is more effective than using extra pillows, which can flex the neck and potentially worsen airway issues. Timing the last meal or snack a few hours before lying down also helps ensure the stomach is empty before a prolonged period of rest.