As evidence linking hearing loss to cognitive decline and dementia mounts, researchers and clinicians are starting to explore whether automated, self-administered cognitive screening tests should be added to routine workups of patients seen in busy otolaryngology practices. Whether the technology behind these automated tests is ready for everyday use depends on whom you ask.
Explore This IssueJuly 2021
What is not up for debate is the reason behind the intense interest in cognitive screening: the epidemiologic data underpinning the connection between hearing loss and brain function. “Whether you look at Frank Lin’s work with the Baltimore Longitudinal Study of Aging or the more recent work by The Lancet Commission on Aging, it’s now clear that hearing loss and cognitive decline are strongly associated,” said Jed Grisel, MD, an otolaryngologist in practice at Texoma ENT & Allergy in Wichita Falls, Texas. “That has profound implications for what we should be doing as a profession to identify these patients and intervene as early as possible.”
There is plenty of research that backs up the link. A recent scientific statement from the American Heart Association underscored the important role adequate hearing plays in a patient’s ability to maintain healthy brain function (Stroke 2021;52:e295-e308). And The Lancet study Dr. Grisel cited, first published in 2017 and updated in 2020 (Lancet 2020;396:413-446), used meta-analyses to identify risk factors for dementia. The investigators found that age-related hearing loss may account for between 8% and 9% of all cases of dementia.
“That’s an incredible number,” said Dr. Grisel. “It far outstripped other risk factors in The Lancet report that many of us typically think of when it comes to dementia contributors, such as hypertension [2%], traumatic brain injury [3%], and smoking [5%].”
That correlation, albeit strong, does not necessarily mean causation, Dr. Grisel stressed. More research needs to be done to prove that treating patients who have hearing loss actually prevents or mitigates cognitive decline. “But we have to start with at least the assumption that it will prove to be the case, and act accordingly with more aggressive cognitive screening,” he said. “This really is a public health mandate, given our aging population and the high stakes involved.”
Frank R. Lin, MD, PhD, the director of the Cochlear Center for Hearing and Public Health and a professor of otolaryngology, medicine, mental health, and epidemiology at Johns Hopkins Medicine in Baltimore, said his work in this area first germinated when he read a 1989 paper linking the two conditions in the Journal of the American Medical Association (1989;261:1916-1919).
“I knew this was just a preliminary finding,” said Dr. Lin. “But it really piqued my interest, in part because it offered a possible explanation for what I was beginning to see in my surgical practice: patients with hearing loss suffering some level of cognitive overload from trying to discern sounds with a steadily diminished ability to do so. This often leads to them feeling isolated from family members and having compromised mental capacity as a result.”