Older adults often have trouble understanding what someone is saying when surrounded by background noise, such as at a restaurant or party, but their ears may not be the only problem. Researchers at the Medical University of South Carolina are studying how much the brain plays a role as well.
Supported by the National Institute on Deafness and Other Communication Disorders, one of the National Institutes of Health, the scientists are presenting their findings at the 2009 Midwinter Meeting of the Association for Research in Otolaryngology in Baltimore.
Using magnetic resonance imaging (MRI), the researchers performed brain scans on 36 older and younger adults as they tested their ability to identify certain words, some of which had been filtered to make them difficult to understand. The researchers analyzed the scans to functionally define speech- and attention-related areas of the brain and then examined the volume of gray matter in those regions for age-related changes.
They found that, in general, older adults were significantly worse at identifying words than younger adults in challenging listening conditions. Even after eliminating variation due to possible hearing loss, these differences in performance corresponded closely to a loss of volume in a small portion of the auditory cortex, a part of the brain that processes what our ears hear. What's more, the relationship between the volume of gray matter in this brain region and the ability to identify words was present in both younger and older adults, suggesting that aging may intensify developmental problems that a person may have in understanding speech.
The findings could help us better understand presbycusis, a type of hearing loss brought on by aging that also involves the brain's ability to process what the ears hear.
Materials provided by NIH/National Institute on Deafness and Other Communication Disorders. Note: Content may be edited for style and length.
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