Swallowing the Consequences of Dysphagia

Dysphagia is the term used to describe a swallowing disorder that usually results from a neurological or physical impairment of the oral, pharyngeal, or esophageal mechanisms (Royal College of Speech and Language Therapists 2014). In fact, the conventional clinical wisdom is that any disruption in the swallowing process may be defined as dysphagia (Crary et al. 2003). Dysphagia can be a transient, persistent, or deteriorating symptom, according to the underlying pathology.

In the United States, dysphagia affects at least 300,000 to 600,000 persons yearly (HHS 1999). Although the exact prevalence of dysphagia across different settings is unclear, conservative estimates suggest that 15% of the elderly population is affected by dysphagia (Barczi et al. 2000). The U.S. Census Bureau indicates that in 2010, the population of persons above the age of 65 was 40 million. This suggests that up to 6 million older adults could be considered at risk for dysphagia.

On another level, and according to one frequently cited study, dysphagia referral rates among the elderly in a single tertiary teaching hospital increased 20% from 2002 to 2007, with 70% of referrals for persons above the age of 60 (Leder et al. 2009). More recent assessments indicate at least 3% of the adult population experiences one episode a week as a result of confounding factors, such as the use of specific medications and presentation of gastroesophageal reflux disease (GERD) (Cho et al. 2015). Interestingly, in many cases, GERD is not clinically diagnosed among those that exhibit dysphagia.

From a mechanical perspective, the “normal” swallow needs the respiratory, oral, pharyngeal, laryngeal, and esophageal anatomical structures to function in synchrony. This coordinated response is dependent upon the motor and sensory nervous system being intact.

Disorders of swallowing are associated with increased likelihood of aspiration, chest infections, and pneumonia. In addition, dysphagia is associated with a reduced quality of life.

A strong relationship appears to exist between dysphagia and the negative health outcomes of malnutrition and pneumonia in patients who have had a stroke or suffer from dementia as well as among community-dwelling elderly adults (Sura et al. 2012). This observation clearly suggests that both normal and abnormal arcs of aging are associated with dysphagia. In light of the fact that the fastest-growing and largest segment of our population is that of older adults, it seems timely to direct significant basic science and clinical investigation in the arena of swallowing dysfunction and the development of unique foods to address it.

Clinical studies have shown that the process of swallowing changes with normal aging, a phenomenon known as presbyphagia. The subtle or “subclinical” age-related changes make older adults more vulnerable to dysphagia during acute or chronic disease insults.

Here are some of the nonpathological anatomical developments that make older adults vulnerable to dysphagia:
1) Reduced bulk, and possibly reduced sensitivity, in the vocal cords that protect the airway. The associated hazard is aspiration and aspiration pneumonitis. 2) Reduced bulk, and possibly strength, in the tongue and pharynx that regulate esophageal motility. 3) The rostral pole of the esophagus is a sphincter that must relax in order to open and allow foods and liquids to enter. With aging, the size of the opening may decrease. The hazard here is that pills or tablets may “get stuck” and/or cause pill esophagitis. 4) The pharynx is longer and more dilated in older adults than in youth. The normal time for a single swallow is about 1 second in younger individuals, but it can be 20% or so longer in older adults. This means that the airway has to be protected for a greater duration in order for safe swallow to occur.

So what might all this mean for the development of foods with texture, consistency, and other sensory qualities that may be valuable adjuncts to the armamentarium of existing therapies for dyspahgia? It is tempting to speculate that this is a potentially valuable and essentially unexplored area for product research and development within the food industry and at the intersection of food, medicine, and health.

The bottom line of dysphagia was nicely summarized by McCulloch et al. in the book Deglutition and Its Disorders. They state, “When a person is unable to swallow, the ability to enjoy almost all other aspects of life is affected. Even minor, intermittent dysphagia can lead to psychological and social stresses. Episodes of choking can lead to a fear of eating that can lead to malnutrition and social withdrawal” (McCulloch et al. in Perlman and Schulze-Delrieu 1997).

Roger Clemens, DrPH, CFS, Contributing Editor
Adjunct Professor, Univ. of Southern California School of Pharmacy, Los Angeles, Calif.
[email protected]