How Aging Affects Swallowing: A Q&A with Sonja Molfenter

Sonja Molfenter, assistant professor of communicative sciences and disorders at NYU Steinhardt, received a grant of more than $413,000 from the National Institute on Deafness and Other Communication Disorders to study dysphagia, or difficulty swallowing. We spoke with her about this common but little-discussed health problem.

What causes dysphagia, and how prevalent is it?
Dysphagia is caused by disruption to the swallowing mechanism. This disruption can occur within the brain, nerves, or the muscles used in swallowing. Some common causes include stroke, brain injury, head and neck cancer, and progressive illnesses like Parkinson’s disease or dementia.

Because of the diverse causes and challenges with defining dysphagia, the incidence and prevalence of swallowing disorders are poorly understood. It has been estimated that up to 22 percent of the population over 50 has difficulty swallowing and that each year 10 million Americans undergo swallowing assessment.

What are some of the issues related to having difficulty swallowing?
Those with swallowing disorders are at risk of experiencing malnutrition, dehydration, and aspiration pneumonia. In the latter case, when food or liquid are not swallowed safely and/or efficiently, it can enter the trachea and the lungs and causes serious respiratory infection.

Because of these risks, patients with dysphagia are often placed on precautions that have serious negative consequences for their quality of life. For example, people with dysphagia are often required to drink thickened liquids because they move more slowly in the swallowing tract. Unfortunately, people with swallowing disorders often avoid family and social events that involve eating and drinking. These quality of life issues are what underlie my motivation to be a swallowing researcher.

Your NIDCD-funded research will focus on age-related muscle loss in the throat and the impact this has on swallowing function. Can you tell us about the research you’ll be conducting, and what you’re hoping to learn?
It is well-known that our muscle strength and coordination decline in the second half of life. This naturally-occurring frailty has been well established in limb muscles, and we know that it is probably happening in the tongue, too. We don’t yet have a good understanding of what is happening to the muscles inside the pharynx, or throat, that are critical for swallowing.

This grant will help me to study whether age-related muscle loss in the throat explains decline in swallowing function. To capture muscle loss, I will be using a device called an Acoustic Pharyngometer. It works kind of like echolocation in bats: sound waves are introduced into the mouth and throat and reflected back into a microphone, which tells me the dimensions of the airspace in the throat. This tool is traditionally used by dentists and is new to swallowing research. I will compare the findings with the gold-standard swallowing assessment (videofluoroscopy), and hope to learn that this non-invasive device can detect changes in throat muscles that represent change in swallowing function. If so, it would mean we could use this device to monitor treatment outcomes and hopefully prevent or delay dysphagia onset in seniors.

How did you become interested in studying swallowing?
I am a clinically-trained speech language pathologist. During graduate school, I had an eight-week clinical externship in a hospital where 90 percent of my caseload involved the assessment and treatment of swallowing disorders. Before that experience, I thought I wanted to work with children who had articulation disorders. After experiencing the fast-paced the medical setting and the major impact a swallowing disorder can have on an individual’s quality of life, I was hooked (my supervisor was proud to have ‘converted’ me). I practiced for two years in dysphagia assessment and management before pursing doctoral level study, which has ultimately landed me where I am today.