Researchers Find Link Between Dementia And Sound Processing

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Main Category: Hearing / Deafness
Also Included In: Alzheimer's / Dementia;  Ear, Nose and Throat
Article Date: 22 Jul 2008 - 0:00 PDT

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People who find it difficult to hear in complex situations with competing noise (such as one conversation among many) are also likely to suffer from mild memory impairment, according to a new study in the July issue of Archives of Otolaryngology-Head & Neck Surgery.

Central auditory processing dysfunction is the term that researchers use for this type of hearing disorder. The diagnosis, the authors write, "Is applied to persons whose hearing in quiet settings is normal or near normal yet who have substantial hearing difficulty in the presence of auditory stressors such as competing noise and other difficult listening situations." It is important for people to have central auditory testing in order to assess the hearing abilities of individuals. The authors add that, "Poor central auditory ability, per se, is not helped by amplification and requires alternative rehabilitation strategies." Earlier research has shown that people with Alzheimer's disease and dementia often demonstrate central auditory processing impairment.

To further study the link between memory loss and auditory capability, George A. Gates, M.D. (University of Washington, Seattle) and colleagues studied 313 individuals who were about 80 years old and who began participating in a dementia surveillance program in 1994. The sample consisted of 232 controls with no memory loss, 17 individuals diagnosed with dementia, and 64 individuals diagnosed with mild memory impairment but no dementia.

The researchers had the participants perform three tests in order to assess the state of their central auditory processing. One test contained nonsense sentences being read at the same time as an interesting narrative, and the other two tests contained separate sentences or numbers that were read into each ear at the same time. The authors note that, "These central auditory processing test paradigms evaluate how well an individual manages competing signals, a task that requires adequate short-term memory and the ability to shift attention rapidly."

The main finding of these tests was that the group with dementia and the group with mild memory impairment had significantly lower auditory processing test scores, on average, than the control group. After statistically controlling for factors such as age and hearing status, the link remained significant.

"Central auditory function was affected by even mild memory impairment," conclude the authors. "We recommend that central auditory testing be considered in the evaluation of older persons with hearing complaints as part of a comprehensive, individualized program to assist their needs in both the aural rehabilitative and the cognitive domains."

Central Auditory Dysfunction in Older Persons With Memory Impairment or Alzheimer Dementia
George A. Gates; Melissa L. Anderson; M. Patrick Feeney; Susan M. McCurry; Eric B. Larson
Archives of Otolaryngology-Head & Neck Surgery (2008). 134[7]: pp. 771 - 777.
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Written by: Peter M Crosta
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