A study conducted by researches at Pennsylvania State University and published in the August 31st., 2011 issue of “Journal of Neuroscience” established a direct link between hearing loss and the loss of gray matter within the primary auditory cortex of older adults.
Using functional magnetic resonance imaging and voxel-based morphometry the research team compared hearing, and the ability to understand complex and simple sentences in a group of older adults and found a direct relationship to hearing ability and relative size of those regions of the brain associated with speech, hearing and understanding.
This research clearly indicates that as the signal stimulus from the peripheral auditory system (the ears) degrades, fewer resources are allocated to processing, resulting in greater difficulty in understanding complex sentence and speech structure. Younger hard of hearing adults with similar understanding difficulties did not show the shrinkage in overall size and volume of these important processing centers, as did their older counter parts.
This study lends further credence to the need for early intervention when even a moderate degradation of signal being received from the ears begins, as this loss is directly related to less recruitment of those adjacent auditory processing centers needed for more complex speech language and understanding processes. Over time this leads to their actual shrinkage.
This study establishes a strong cascading effect over time, complete with which structures are most effected by this failure to adequately stimulate. The implications involve other higher processing functions having direct bearing on maintaining mental health over all, as well as just effecting communications, becoming ever more evident, as available gray matter is shown to shrink from lack of stimulation.
This new study, while establishing very clearly the correlations between loss of hearing and loss of gray matter in older adults isn’t really news to those working with the hearing impaired, as studies conducted by the VA and published in the early nineties established a loss of speech understanding ability over time, when comparing aided versus unaided ears in veterans with hearing loss. What it does, is correlate this loss of understanding over time with an associated loss of gray matter within those structures associated with speech processing and understanding.
While not putting it quite this way, I’ve been telling my patients for years of the need for early intervention in hearing loss to maintain speech understanding over time. Now this study indicates that those who choose not to correct even a moderate hearing loss, risk the loss of actual brain matter over time.
The study clearly indicates that if the primary auditory cortex doesn’t get properly stimulated, the effects cascade throughout the entire central nervous system, resulting in time, in the long term loss of not only our ability to understand complex speech, but also to accomplish other complex reasoning and processing as well.
Nature’s law, “Use it, or loose it.” Exercise has clearly been shown to extend to the brain.
R. D. ‘Dan’ Taylor, ACA, BC/HIS, COHC
A Advanced Hearing Care
720 East New Haven Avenue Suite 12
Melbourne, Florida 32901