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Rock Doc: Hearing loss may bring bigger issues

Mon., March 4, 2013


That simple question gets asked by many people as they age and hearing loss begins to creep into daily life. Before my elderly mother got her hearing aids, it was a frequent refrain around my house.

Now we are learning that hearing loss affects more than conversational patterns. A recent study headed by Dr. Frank Lin of Johns Hopkins School of Medicine looked at the effects of hearing loss on issues of mental decline. The study was published in JAMA Internal Medicine, and I read about it on the ScienceNews website.

Lin and his colleagues studied almost 2,000 adults in their 70s on average. About 1,200 of the subjects had at least some hearing loss, namely problems hearing sounds of less than 25 decibels – on the order of a whisper. That’s not unusual or surprising: More than half of Americans older than 70 have some degree of hearing loss.

Lin followed the participants in his study for six years. During that time, he and his colleagues measured their attention span, short-term memory and ability to rapidly match numbers to symbols.

As the subjects in the study aged, they went downhill on these cognitive tasks. That’s the bad news for all of us: Aging takes its toll on cognition. But the more surprising result was that those people who had hearing loss went downhill on the cognitive tasks sooner than those who were aging but who could hear well. For those with hearing loss, the drop in cognitive ability came about three years earlier than for the other seniors studied.

As a good scientist, Lin knows that an association between cognitive decline and hearing loss doesn’t prove that one element of our lives is necessarily causing the other. But other studies have sketched how hearing loss might harm brain function. For one thing, people who know they don’t hear well – those often saying “What?” and annoying their conversational partners around them with that question – might avoid social situations. And social isolation isn’t good for brain function.

“Social isolation is a major, major factor for dementia and cognitive decline,” Lin said to ScienceNews.

People with poor hearing work hard to hear all they can. There’s good reason to think their brains have to divert extra energy to the work of trying to decode and interpret poorly heard sounds around them. That’s significant because the brain only has so much “juice” for working on a moment-by-moment basis. Things like making fresh memories may suffer if the brain is working hard trying to hear what is being said, according to University of Toronto audiologist and psychologist Kathy Pichora-Fuller.

Those involved in the recent study agree more work is needed to show how poor hearing may be linked to cognitive decline. One avenue worth exploring is whether hearing aids can help shore up mental functioning.

That would be news worth hearing.

E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.

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