Interview with Frank R. Lin, MD, PhD
AudiologyOnline: Dr. Lin, thanks for your time today. How common is hearing loss, based on the latest data?
Dr. Frank Lin: As you know, sensorineural hearing loss that occurs from aging and other processes that can damage the inner ear over time is extremely common over the lifespan. When hearing loss is defined objectively using pure tone audiometry, we observe that the prevalence of a clinically-significant hearing loss nearly doubles with each age decade such that nearly two-thirds of all adults over 70 years have a meaningful hearing loss. In turn, we also know that less than 20% of these adults with hearing loss and who could benefit from amplification currently use a hearing aid.
Because most hearing loss occurs gradually and insidiously over years, we know that many adults are unaware of their loss. Central compensation with recruitment of other brain regions to aid in auditory processing and increased use of contextual cues allows many individuals to still decode the impoverished ascending auditory signal and to effectively “hear.”
AudiologyOnline: We know that hearing loss impacts healthy aging. Can you elaborate on the role of hearing and the impact of hearing loss on aging?
Dr. Frank Lin: Healthy aging can broadly be defined as maintaining optimal cognitive, physical, social, and mental functioning as we age. A conceptual model based on current research evidence describes the mechanisms through which hearing loss could affect these broad functional domains.
This model acknowledges that a set of common etiologies could underlie a simple correlation between hearing and poor health outcomes. These include but are not limited to: age, vascular risk factors (e.g., diabetes, smoking), and social factors (e.g., education). Clearly, if these common etiologies were the only reasons underlying an association between hearing and outcomes such as dementia, this would not be interesting from the clinical or public health perspective (e.g., treating hearing loss wouldn’t make a difference on helping reduce the risk of dementia). In contrast, mechanistic pathways through which hearing loss could directly contribute to poorer health include the effect of hearing loss on cognitive load, changes to brain structure, and decreased social engagement.
AudiologyOnline: What are the implications of treating hearing loss?
Dr. Frank Lin: The importance of hearing loss in the context of public health is that the broader functional consequences that have been associated with hearing loss may, in fact, be reduced with hearing loss treatment. The mechanistic pathways potentially linking hearing loss with impaired cognition are important because these pathways may be modifiable with existing hearing rehabilitative interventions that incorporate the use of sensory aids to maximize the clarity of speech signals and educational counseling to teach communicative strategies and the effective use of devices. Importantly, previous studies provide proof-of-principle that hearing aids and interventions that provide enhanced auditory stimuli can engage and modify the hypothesized mechanistic pathways linking hearing and cognition through reducing cognitive load, altering functional pathways and brain structure, and improving social engagement.
However, determining whether treating hearing loss could, in fact, reduce the risk of adverse outcomes such as cognitive decline and dementia is difficult. Intuitively, one would think that we could simply compare individuals with hearing loss who do versus do not use hearing aids in past epidemiological studies of older adults. However, individuals who use hearing aids are often also more likely to be more affluent, better educated, and healthier — all of which bias hearing aid use to appear to be associated with better outcomes when in fact the other factors associated with hearing aid use are what would explain the better results. Definitively determining whether treating hearing loss could reduce the risk of adverse health outcomes will require a randomized trial in which a large cohort of older adults are randomized to hearing intervention versus a control intervention. Fortunately, such a trial (Aging and Cognitive Health Evaluation in Elders) has been funded by the National Institutes of Health and is currently ongoing, but definitive results will not be available until 2022.
AudiologyOnline: We have a wide range of readers interested in this topic. Maybe this is a good opportunity to briefly mention some additional strategies that are helpful for people with hearing loss.
Dr. Frank Lin: Simple strategies to optimize communication can make a huge difference for the majority of individuals with hearing loss. These include:
- When possible maintain face-to-face communication and turn down any background noise when speaking to the individual.
- Re-wording rather than simply repeating phrases over and over again if the individual did not initially understand (e.g., if asking “what did you think of the meal?” was not understood, try repeating once and then rewording as “how was the food?”). This allows the individual to use contextual cues to understand the meaning when speech understanding is affected by hearing loss.
- Consider taking advantage of new assistive listening technologies for those individuals with marked difficulty understanding in various face-to-face scenarios and over the phone.
Aging America & Hearing Loss: Imperative of Improved Hearing Technologies: White House President’s Council of Advisors on Science and Technology, October 2015
Hearing Health Care for Adults: Priorities for Improving Access and Affordability. National Academies Press. Washington, D.C. 2016.
IOM (Institute of Medicine) and NRC (National Research Council). Hearing loss and healthy aging: Workshop summary. Washington, D.C.: The National Academies Press; 2014.
Lin FR, Albert M. Hearing loss and dementia - who is listening? Aging Mental Health 2014;18(6):671-3.
Lin FR, Metter EJ, O’Brien RJ, Resnick SM, Zonderman AB, Ferrucci L. Hearing loss and incident dementia. Arch Neurol 2011;68(2):214-20.
Lin FR, Niparko JK, Ferrucci L. Hearing loss prevalence in the United States. Arch Intern Med 2011;171(20):1851-2.
Livingston G, Sommerlad A, Orgeta V, Costafreda SG, Huntley J, Ames D, et al. Dementia prevention, intervention, and care. Lancet 2017.