Swallowing difficulties associated with neurological disorders may increase the risk of pneumonia, according to researcher Don Bolser of the University of Florida, who studies coughing mechanisms.
Air enters the lungs through the larynx, which is close to the esophageal sphincter. The brain coordinates the opening of the larynx and esophageal sphincter to ensure that breathing, eating and drinking occur at the right times, and that the lungs only get air and the esophagus only food and liquids.
The process usually runs smoothly. When it doesn’t, we choke – that’s the body’s defense to prevent food and liquids from reaching the lungs.
But many people with neurological diseases, such as multiple sclerosis, Alzheimer’s, Parkinson’s, ALS and stroke, have swallowing difficulties because their brains have a harder time coordinating breathing, eating and drinking. This increases the risk of them inhaling food and liquids into the lungs, which can lead to death by pneumonia or choking.
“Impaired swallowing is associated with many conditions of the elderly, and it is often severely underreported,” Bolser wrote in a news release. “Clinicians may not detect it or may see it as a side effect of another condition.
“As a neuroscientist who has studied brain diseases, I know of no pharmaceutical companies that have drug discovery programs aimed at restoring weakened swallow and cough,” he added. “And yet, it’s a major problem.”
Coughing is a reflex the body uses to expel unwanted material. People with brain diseases cough less, Bolser said. Or they have less ability to activate breathing muscles to create airflows that can eliminate material from the lungs.
These problems stem from the fact that brain diseases affect neurons that control coughing and respiratory muscles. An inability to protect the lungs and airways from food and drink raises the risk of a person getting pneumonia or choking.
“Sometimes the swallowing impairment, rather than the primary brain disease, actually leads to death,” Bolser wrote. “When swallowing is impaired, it is more likely that material will enter the lungs and trachea during eating or drinking. This is known as aspiration. Aspirated food or drink ‘seeds’ the lungs with material that is coated with pathogens from the mouth. These pathogens are not normally present in the lungs and can cause chronic inflammation and serious bouts of pneumonia.”
Bolser said aspiration pneumonia is costly. One hospital admission can be as high as $17,000, and the cost of treating the disease nationwide was $4.4 billion in 1997. The condition also affects half of long-term care residents.
“When members of our research team talk to their friends about airway protection and its consequences, everyone seems to have a story,” Bolser wrote. “Most center around an older relative who had a brain disorder and the difficulties this person had eating. Often their relative choked when eating or had to eat special thick foods. These are signs of impaired swallow, cough and aspiration.”
One strategy for decreasing the risk of aspiration pneumonia is to eat thick and solid foods, which are less likely to go into the airways during swallowing.
There are no drugs to improve swallowing. Some companies have built devices that electrically stimulate the neck to help in swallowing. But Bolser wrote that there is a debate about the long-term benefit of the devices, and no evidence that they strengthen coughing.
A group in Japan reported that a combination of menthol and capsaicin, which is present in red peppers, showed promise in helping elderly people with serious swallowing problems and reducing the risk of aspiration pneumonia.
“In short, while there are some promising approaches, there are no widely accepted therapies for restoring weakened swallow and cough in patients at significant risk of aspiration,” Bolser wrote. “Continued research on the fundamental neurological mechanisms of coughing and swallowing will provide a foundation for new therapies to reduce the occurrence and severity of aspiration pneumonia.”