Dr. Kujawa concluded her talk by explaining that once a synapse is destroyed, the neuron is functionally disconnected and can therefore carry no auditory information unless it is stimulated directly. Although threshold detection tasks do not require a full population of intact neurons, the investigators expect that such synaptic and neural loss contributes to speech-in-noise difficulties and tinnitus, two common complaints that can occur with or without threshold elevations.
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November 2017Hearing Loss and Cognition
Jing Shen, PhD, research assistant professor in the department of communication sciences and disorders at Northwestern University, followed up with a presentation on association of hearing loss with cognitive decline in the elderly. She said that nearly half of the population older than age 65 has hearing loss, and this vulnerable population is expected to double in size over the next two decades.
As Dr. Dhar noted, this hearing loss may actually begin in the mid-20s. Possible explanations for cognitive decline associated with hearing loss in the elderly include neural loss with aging, social isolation, and negative consequences on cognitive load with hearing loss. For older patients, she emphasized earlier detection and treatment for hearing loss and awareness of cognitive changes.
Future of Auditory Science
During the discussion, the investigators delivered a message to clinicians: Do not ignore a patient who claims hearing loss but tests normally on an audiogram, no matter their age. These patients may be experiencing a hidden hearing loss that is not an audibility problem, per se. While they may pass the simple tests for hearing loss, they might be having trouble focusing on and processing sounds in complicated situations.
As scientific understanding of hearing loss increases, the tests for hearing loss will change, leading Dr. Lalwani to conclude, “Our testing paradigms for “routine” audiometry will significantly change in the next few years to be able to detect these hearing loss[es] that currently remain hidden.” The new research in auditory science creates a great foundation to make those changes.
Dr. Pullen is a freelance medical writer based in Illinois.
Take-Home Points
- There is a current lack of sound sources that can deliver clean but intense signals to evaluate the parts of the inner ear responsible for capturing the highest audible frequencies.
- Hearing loss begins between the ages of 25 and 29 years, much earlier than is commonly thought.
- Significant injury can be “hidden” in a normal threshold audiogram.
- Do not ignore a patient who claims hearing loss but tests normally on an audiogram.