TUESDAY, Nov. 29, 2016 (HealthDay News) -- Seniors who struggle to make out what people are saying around the dinner table or on a noisy street may have perfectly "normal" hearing. The problem could actually be in the brain, a new study suggests.
Trouble
processing conversations in a loud setting may indicate that the
brain's ability to quickly and easily process speech is diminished.
The
findings demonstrate that "separately from any typical hearing loss
that might occur as we age, our brains also get worse at processing the
sound of talking when there are other sounds at the same time," said
study co-author Jonathan Simon. He's an associate professor at the
University of Maryland's Institute for Systems Research.
"The background noise may not even be considered especially loud by younger listeners," he noted.
But
"the implication is that typical older adults need to exert more
effort, and take more time, in order to understand what someone is
saying to them when there's also noise, even only moderate noise, around
them," Simon explained.
About one in three Americans aged 65 to
74 has some degree of hearing loss, according to the U.S. National
Institute on Deafness and Other Communication Disorders. For those 75 or
older, half have difficulty hearing.
The new study included 17
young adults (aged 18 to 27) and 15 older adults (aged 61 to 73). All
had normal hearing and were dementia-free.
All had a series of
hearing tests, some of which included background noise. All also
underwent brain scans focused on two regions of the brain: the midbrain,
which controls basic sound processing; and the cortex, which is
critical to speech comprehension.
Younger adults performed
significantly better than seniors in both quiet and noisy settings. But
the researchers found that noisy settings were more challenging for
seniors.
The scans suggested why.
Midbrain scans revealed
that neurological signaling related to hearing was weaker among the
older study participants. And cortex scans suggested that auditory
information took longer to process among seniors than young adults.
Why?
The study authors theorized that the problem could trace back to normal
age-related nerve impairment that undermines signaling and
communication between nerve cells in the brain.
Regardless, the bottom line was clear: seniors often have to expend more effort to hear, and often end up with worse results.
"Typical
seniors who have difficulty understanding what someone is saying in a
noisy room will have both kinds of degradation," said Simon, referring
to loss of actual hearing function as well as brain-processing problems.
And
that means that while hearing aids "may be an important part of any
solution to general problems with hearing," they don't solve the whole
problem, Simon said.
The solution, he added, could be a kind of physical therapy for hearing and speech recognition.
"There
is -- in theory, not yet in practice -- a real possibility of restoring
enough of the youthful aspects of the brain to help with this problem,"
Simon said.
Robert Frisina directs the University of South
Florida's Global Center for Hearing and Speech Research, in Tampa.
Though he was not involved with the new research, he called "the
Maryland study a good advance in this area."
"Now, it is pretty
well accepted that neurodegenerative changes in the parts of the brain
used for hearing play a significant role in age-linked hearing loss and
speech perception problems, particularly in background noise," he said.
"As
the aging brain is understood more and more at molecular levels, these
molecular changes become the prospective targets for drug or medication
interventions," Frisina added.
Future interventions may ultimately involve a combination of both hearing therapy and cutting-edge medicine, Frisina said.
The study was published recently in the Journal of Neurophysiology.
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