Comments on “Listening Is Where Hearing Meets the Brain…in Children and Adults”

Dear Editor: The recent article by Douglas Beck, PhD, and Carol Flexer, PhD,1 (February 2011 HR) raises important questions for audiologists and neurologists alike. We would like to add to this discussion.

Recently, Lin et al2 demonstrated that people with hearing impairment are at greater risk for developing dementia as they age. This does not establish causality, but reveals a relationship between cognition and audition. The study reveals that, the greater the hearing loss, the greater the chance of developing dementia.

Palmer et al3 reported that diseases can interact, such that the comorbid result is worse than either disease in isolation. Arlinger4 reported that hearing loss initiates a number of negative consequences and disabilities, including poor quality of life from isolation, depression, feelings of exclusion, and a loss of cognitive function. Research on aging suggests that compromised auditory input exacerbates cognitive deficits.

In addition, cognitive level has been found to be a predictor of successful hearing aid use.5 These cognitive abilities enable hearing aid users to “fill in the blanks,” by using cognitive and lexical reserves when listening in environments with a poor signal-to-noise ratio. The more demanding the task of listening, the less cognitive reserve is available to decode and understand. Ultimately, this leads to social isolation.

When a patient presents with a possible cognitive deficit, the issue of hearing loss should be explored. Therefore, there should be a low threshold to refer for audiological evaluation. This evaluation includes tests for speech recognition ability in quiet and in noise. If indicated, binaural amplification improves both speech recognition in noise and localization ability (eg, a safety issue when crossing the street). This also reduces the patients’ cognitive burden while listening to conversations in noisy environments.

We propose that patients being evaluated for cognitive deficits be considered for referral to an audiologist for a comprehensive audiological evaluation and, if indicated, amplification. An area of potential study could be to assess cognitive functioning subsequent to a successful hearing aid fitting.

References
  1. Beck DL, Flexer C. Listening is where hearing meets the brain…in children and adults. Hearing Review. 2011;18(2):30-35.
  2. Lin FL, Metter EJ, O’Brien RJ, Resnick SM, Zonderman AB, Ferrucci L. Hearing loss and incident dementia. Arch Neurol. 2011;68(2):214-220.
  3. Palmer CV, Adams SW, Bourgeois M, Durant J, Rossi M. Reduction in caregiver-identified problem behaviors in patients with Alzheimer disease post hearing aid fitting. J Sp Lang Hear Res. 1999;42:312-328.
  4. Arlinger S. Negative consequences of uncorrected hearing loss—a review. Int J Audiol. 2003;42(Suppl 2):2s17-20.
  5. Pichora-Fuller MK. Audition and cognition, where the lab meets clinic. ASHA Leader. 2008;13(10):14-17.

—Arthur Podwall, PhD, Syosset Speech and Hearing Center, Syosset, NY, and David Podwall, MD, Neurological Associates of Long Island, NY

Response from Drs Beck and Flexer: Thank you for your thoughtful response and insight. We agree with your observations and recommendations, and we believe your Letter to the Editor underscores and helps “bridge the gap” between cognitive deficits and hearing loss. Indeed, when appropriate, binaural amplification does improve speech recognition in noise, binaural processing, and localization ability, and reduces cognitive burden.

Lastly, we agree with your recommendation: it would clearly be in the patient’s best interest to obtain complete audiometric evaluations on all patients suspected of cognitive deficits.