Expert Roundtable | September 2015 Hearing Review

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Douglas L. Beck, AuD

Editor’s Note: This special edition of The Hearing Review was recognized as a finalist in the FOLIO: Eddies Award, an award akin to the “Academy Awards” of trade publishing. Congratulations to Dr Beck and all the authors who participated.

This series of articles is a review of the key points addressed during the 2015 AudiologyNOW! featured session titled “Issues, Advances, and Considerations in Cognition and Amplification” on March 26, 2015, San Antonio, Texas. As moderator for this exciting event, I was honored to work with my friends and colleagues Brent Edwards PhD, Jason Galster, PhD, Andrea Pittman, PhD, Gabrielle Saunders, PhD, Christian Füllgrabe, PhD, and Gurjit Singh, PhD. Indeed, this feature session was enthusiastically attended by some 400 audiologists from across the globe. Of course, an event of this size requires immense coordination and cooperation, and I am especially grateful to my friend and colleague Jason Galster, who co-chaired and co-managed the session. Special thanks to Jason for his friendship, insight, expertise, and willingness to make and receive phone calls and emails in the wee hours of the night. — Douglas L. Beck, AuD, guest editor

Chapter 1: The State of the Art: Hearing Impairment, Cognitive Decline, and Amplification, By Douglas L. Beck, AuD (see below)

Chapter 2: Cognitive Function and the Patient Landscape, By Brent Edwards, PhD

Chapter 3: Beyond Audibility: The Role of Supra-threshold Auditory Processing and Cognition in Presbycusis, By Christian Füllgrabe, PhD

Chapter 4: Hearing Aid Outcomes and the Influence of Non-auditory Factors, By Gabrielle Saunders, PhD

Chapter 5: Examining Relationships Between Cognitive Status and Hearing Aid Factors, By Jason Galster, PhD

Chapter 6: The Amplification of New Information, By Andrea Pittman, PhD

Chapter 7: Why Cognition Matters For Hearing Care Professionals, By Gurjit Singh, PhD, CASLPO

 

The State of the Art: Hearing Impairment, Cognitive Decline, and Amplification

Chapter 1: A review of contemporary research…and what it might imply for our future

The brain, cognition and amplificationNew and important information addressing hearing, listening, the brain, cognition, amplification and more will be presented here. I would argue the time has come to re-define the goal from “hearing” to “maximal listening.” That is, our task is to provide a maximal bottom-up (ie, sensory) signal, so the top-down (ie, cognitive) task is easier and more efficient. When the brain receives a more natural and accurate auditory signal, it requires less brain power to untangle and interpret the same.

Hearing is a basic sensory, bottom-up (BU) function and may be defined as the perception of sound. Humans are not very good at hearing when compared to many other animals (dogs, cats, whales, and more). However, humans have an amazing and unmatched ability to listen. Listening is a highly sophisticated cognitive, top-down (TD) process which may be defined as applying meaning to sound.

As hearing healthcare professionals, I believe we need to change the focus of our interventions from simply “hearing” to “maximal listening.” Of course, hearing is a prerequisite to listening, and indeed, “Listening is Where Hearing Meets Brain.”1

Clearly, the primary complaint we each address daily is our patients’ inability to understand speech in noise. Of note, the ability to understand speech in noise requires two ears and one brain. That is, the ears’ task is to deliver accurate (ie, undistorted), natural, complete sound to the brain (ie, “hearing”). The brain’s task is to compare and contrast the sound from the left and right sides (with respect to loudness and timing/phase) and to process, interpret, and apply meaning to the delivered sounds (ie, “listening”).

Multiple studies have indicated that hearing loss may be a significant causative factor with regard to cognitive decline in older adults. Further, although admittedly speculative, it has been proposed the association between hearing loss and cognitive impairment could be the result of an underlying common pathology. That is, could the etiology of hearing loss and cognitive decline share a common foundation, such as vascular disease? The relationship between cognitive function, cognitive decline, hearing, hearing loss, listening ability—and the potential to maintain or (perhaps one day) improve cognitive ability through amplification remains promising, but essentially unknown and as of yet unproven, in 2015.

Certainly we know brains change and “re-wire” as a result of auditory deprivation, and we know when the brain is not stimulated via audition, the auditory processing centers in the temporal lobe can (and do) become recruited to perform other brain functions such as somatosensory and visual processing functions.2 Although it appears that amplification may offer promise for the hearing-impaired patient to help maintain or improve cognitive function, those studies are as yet incomplete. However, new and important information specifically addressing these (and related) concerns are being published, availing a stream of interesting and related information.

For example, Lin3 reported in the Journal of the American Medical Association (JAMA) that hearing loss is independently associated with accelerated cognitive decline. That is, for older people with hearing loss, cognitive decline is more apparent than for older people with normal hearing.

In a recent study of people with cochlear implants, Mosnier et al4 concluded that hearing rehabilitation through cochlear implantation “results in improvements in speech perception and cognitive abilities and positively influences their social activity and quality of life.” Clearly, there are differences in patients who receive cochlear implants (CI) and those who receive hearing aids. In general, cochlear implant patients have experienced auditory deprivation for longer periods of time, and the CI patient is arguably more likely than the hearing aid patient to have experienced social isolation, depression, anxiety, and significant degradation with regard to quality of life (in general), thus rendering the CI patient different from the typical hearing aid patient.

Likewise, in a study published this year, Deal et al5 tested the hypothesis that hearing impairment (HI) is associated with lower cognitive function. The researchers evaluated 253 people (mean age of 77 years) with respect to their pure-tone averages and their cognitive status over a 20-year period. Cognitive evaluations were performed in 1990-1992, 1996-1998, and in 2013. Better-ear pure-tone averages (PTAs) from 500 to 4,000 Hz were also evaluated. Subjects were grouped into gross categories according to their PTAs as having either normal, mild, or moderate-to-severe hearing loss. Of note, when comparing people with normal PTAs to those with moderate-to-severe hearing loss, the rate of decline over the 20-year period differed by approximately one-half of a standard deviation with regard to memory, and one-third of a standard deviation with respect to global function. The authors report cognitive declines were greatest among participants who had hearing loss but had not worn hearing aids.

However, Deal et al report the effect of amplification on cognitive decline remains unknown. They concluded in their study a “moderate association between moderate-to-severe hearing impairment and memory performance…this association was strongest among persons with moderate-to-severe HI who reported not wearing a hearing aid.”5

As such, unraveling the relationship between cognitive ability, cognitive decline, and hearing loss is receiving increasing and significant attention from researchers across the globe.

When I look into my crystal ball (always a dangerous thing to do!), I must admit it appears the loose ends are being tied together and it seems extremely likely we will soon have peer-reviewed scientific data which is likely to support the presumption that improving the quantity and quality of sound received by the human brain (ie, preserving and delivering the highest quality, least distorted sound possible) will make the brain’s auditory tasks easier and more accurate.

Specifically, our goal as hearing healthcare professionals may soon be redefined from simply making sound audible, to the provision of maximal natural auditory information—to provide a maximal “bottom-up” or “sensory” acoustic image which maintains interaural loudness and phase relationships and more. This auditory information would require less energy (less processing power) to recognize amplified sounds, thus allowing more cognitive resources to interpret (apply meaning to) sound.

References and Resources

  1. Beck DL, Flexer C. Listening is Where Hearing Meets Brain in Children and Adults. Hearing Review. 2011; 18(2)[Feb]:30-35. http://www.hearingreview.com/issues/articles/2011-02_02.asp

  2. Sharma A. Cochlear implants, brain reorganization, and hearing loss: Interview with Anu Sharma, PhD. June 24, 2015. Available at: http://www.audiology.org/news/cochlear-implants-brain-reorganization-and-hearing-loss-interview-anu-sharma-phd

  3. Lin FR, Yaffe K, Xia J, Xue QL, Harris TB, Purchase-Helzner E, Satterfield S, Ayonayon HN, Ferrucci L, Simonsick EM. Hearing loss and cognitive decline on older adults. JAMA Intern Med. 2013 Feb 25;173(4):293-9. doi: 10.1001/jamainternmed.2013.1868

  4. Mosnier I, Bebear JP, Marx M, Fraysse B, Truy E, Lina-Granade G, Mondain M, Sterkers-Artières F, Bordure P, Robier A, Godey B, Meyer B, Frachet B, Poncet-Wallet C, Bouccara D, Sterkers O. Improvement of cognitive function after cochlear implantation in elderly patients. JAMA Otolaryngol Head Neck Surg. 2015; 141(5)[May 1]:442-50. doi: 10.1001/jamaoto.2015.129

  5. Deal JA, Sharrett AR, Albert MS, Coresh J, Mosley TH, Knopman D, Wruck LM, Lin FR. Hearing impairment and cognitive decline: A pilot study conducted within the atherosclerosis risk in communities neurocognitive study. Am J Epidemiol. 2015;181(9):680-690. Available at: http://aje.oxfordjournals.org/content/181/9/680.abstract

  6. Beck DL, Edwards B, Pichora-Fuller MK. (2011) Exploring the maze of the cognition-audition connection. Hear Jour. 2011;64(10):21-24.

  7. Beck DL and Edwards B, Humes LE, Lemke U, Lunner T, Lin FR, Pichora-Fuller MK. Expert roundtable: Issues in audition, cognition, and amplification. Hearing Review. 2012;19(09):16-26. Available at: http://www.hearingreview.com/2012/09/expert-roundtable-issues-in-audition-cognition-and-amplification

Douglas Beck, AuD, is director of professional relations at Oticon Inc, Somerset, NJ.

Correspondence can be addressed to HR or Dr Beck at: [email protected]

Original citation for this article: Beck DL. The state of the art: Hearing impairment, cognitive decline, and amplification. Hearing Review. 2015;22(9):14.

This article is the first of seven chapters in a series of articles that review the key points addressed during the 2015 AudiologyNOW! session titled “Issues, Advances, and Considerations in Cognition and Amplification.” Follow the links to subsequent chapters by Brent Edwards PhD, Christian Füllgrabe, PhD, Gabrielle Saunders, PhD, Jason Galster, PhD, Andrea Pittman, PhD, and Gurjit Singh, PhD.