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  • [♪ INTRO]

  • Getting older is hard.

  • Not only do your clothes go out of  fashion and slang stops making sense,

  • but you could also lose your hearing  and even experience cognitive decline.

  • And as it turns out, those  two things might be related.

  • The hearing loss and cognitive stuff, that is.

  • Several studies show that there's a  link between hearing loss and dementia,

  • though scientists are still working to  understand exactly what's causing it.

  • While that sounds like it doesn't bode  well for the majority of elderly people

  • who experience some extent of  hearing loss, this may be good news.

  • Because, while we don't have  a cure for dementia right now,

  • we do have treatments for hearing  loss, so if hearing loss is a

  • contributor to dementia, we  can do something to prevent it.

  • Now the termhearing lossrefers toprocess that happens to people who had

  • average hearing earlier in life, and  experienced a decline in hearing as they aged.

  • This can come from all sorts  of sources, like loud sounds

  • damaging your hearing cells, genetics  making you more susceptible to

  • that sound damage, age-related  brain cell deterioration,

  • and insufficient energy for  hearing cells to function.

  • As it turns out, about two-thirds of adults

  • over 70 years old in the  US experience hearing loss.

  • And that's a lot of people!

  • And the extent of their hearing  loss isn't the same, either.

  • As with most things in life, hearing  falls somewhere on a spectrum.

  • To get a measurement of the  extent of someone's hearing loss,

  • they can either fill outquestionnaire or take a hearing test.

  • The hearing test plays sounds  at different intensities to

  • identify the range of sounds  that the person can hear.

  • If the test results show that they  can't consistently hear sounds

  • softer than 25 decibels, then  they're considered to have

  • clinical hearing loss, although  the exact cutoff can vary.

  • So everyone has a different  cutoff volume where you can

  • no longer consistently hear sounds.

  • It's called your pure-tone average, or PTA score.

  • The higher your score, the  more severe your hearing loss.

  • If your PTA score is high enough  for a formal hearing loss diagnosis,

  • then you might have the  option to wear hearing aids to

  • increase the range of sounds you can detect,

  • making hearing aids an effective  treatment for a common problem.

  • The trouble is, only 14% of the people  who need them actually wear hearing aids.

  • Many people never even seespecialist for hearing loss,

  • thinking that cranking up their TV volume is just

  • another trivial part of getting olderjust like a penchant for hard candies.

  • But we're starting to learn  that age-related hearing loss,

  • when untreated, could increase  your risk for developing dementia.

  • A 2011 study from Johns  Hopkins University found that

  • the risk of dementia was increased in  people with age-related hearing loss.

  • Participants with average hearing had lower  risk than those with mild hearing loss,

  • who had lower risk than participants  with moderate hearing loss,

  • who had lower risk than those  with severe hearing loss.

  • So that would suggest that  the worse your hearing gets,

  • the greater your risk of dementia becomes.

  • And that's not all.

  • A 2019 study out of Columbia  and George Washington University

  • found that this effect isn't limited to  the most extreme cases of hearing loss.

  • The participants in this study that didn't  meet the clinical threshold for hearing loss

  • still showed cognitive declines compared  to people without any hearing loss.

  • On average, participants with  PTA scores between 1 and 10

  • scored higher on cognitive tests than  participants with scores of 11 to 20.

  • So even a 10 decibel loss  was significantly associated

  • with cognitive impairment  across a variety of tests.

  • What's more surprising is that this  association is even stronger for participants

  • with PTA scores between 1 and 25  compared to those with scores above 25.

  • All this might be a sign that doctors  should reconsider that clinical hearing loss

  • cutoff of 25 decibels so they could detect

  • and treat more subtle hearing loss  that also affects your cognition.

  • That said, we probably can't go  update all the medical textbooks

  • with a new cutoff until we identify  what a better threshold even would be.

  • And we still need more data  to say that hearing loss

  • causes dementia in the first place.

  • What we've described so far are associations  between hearing loss and dementia,

  • but it's not clear if the hearing loss is  actually causing the cognitive declines.

  • It could be a link in the chain  that leads to dementia, though.

  • That 2011 paper pointed out that  people who experience hearing loss

  • have to put more of their  mental resources toward hearing,

  • which may leave fewer resources  for things like memory.

  • On top of that, people experiencing  hearing loss may be socially isolated

  • because communication becomes more difficult.

  • And there's data linking  social isolation with dementia.

  • So hearing loss could indirectly lead to dementia

  • by preventing communication  and social interactions.

  • Or hearing loss and dementia  could both be symptoms of some

  • other widespread problem like vascular disease.

  • Which would mean that hearing loss could  be a red flag that dementia is brewing.

  • And there's data to back up this red flag idea.

  • The 2011 study showed that people  who developed dementia lost about

  • double the decibels of hearing per year  compared to those who didn't develop it.

  • But whether or not hearing loss  causes those cognitive declines,

  • the big question is if there's  anything we can do about it.

  • If hearing loss is in some way responsible  for people developing dementia,

  • then treating the hearing loss should prevent it,

  • which is where hearing aids come in.

  • But early research into this prevention  technique wasn't terribly promising,

  • showing no association between  self-reported hearing aid use and dementia.

  • But those researchers didn't design  their experiment around hearing aids.

  • The 2011 study didn't include any  data on how often participants

  • wore their hearing aids, what  kinds of devices they used,

  • or even if the participants were using  the right device for their diagnosis.

  • And some scientists think it could take years  for the effect of hearing aids to kick in.

  • So if people who just started wearing  hearing aids were mixed in with people

  • who have been wearing them for yearsthe results would be harder to interpret.

  • So at that point there was  a lot left to be understood

  • about the role of hearing  aids in cognitive decline.

  • And, good news, other studies  were already under way!

  • In 2018, a study that followed up with  participants over 25 years concluded that

  • people who wore hearing aids  were at lower risk of dementia.

  • Now, that study was based on how well  the participants thought they could hear,

  • rather than performance in hearing tests.

  • And while that metric is correlated  with hearing test outcomes,

  • it's not quite as empirical as tests  that define their exact decibel loss.

  • So the perfect experiment  hasn't been conducted yet.

  • But none of the studies conducted so far say that

  • using hearing aids is worse than not using them.

  • And dementia still isn't reversibleso if hearing loss is causing dementia,

  • raising the hearing loss threshold and

  • actually implementing the treatments  available could change lives.

  • It's a testament to modern medical research that

  • we're starting to figure out this relationship.

  • And you heard it here first.

  • If you're still watching at the end of this video,

  • you probably agree that dementia and  memory loss need to be understood better.

  • And if you want to understand memory in a new way,

  • you can take the Brilliant course  on Artificial Neural Networks.

  • This course offers 28 interactive  lessons, including Long Short-Term Memory,

  • which teaches you how models process new data

  • by remembering what they just processed.

  • Brilliant's interactive courses  are made by dedicated math

  • and science educators and lifelong  learners from MIT, Caltech, Duke, and more.

  • But that doesn't mean you have to be  a college student to keep learning.

  • Brilliant courses are designed  for people of all levels,

  • so you can just jump in at any  point and work your way to mastery.

  • Brilliant has supported SciShow videos  for years, including this video!

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  • [♪ OUTRO]

Thanks to Brilliant for  supporting this SciShow video!

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B1 中級 美國腔

Dementia and Hearing Loss are Tightly Linked

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    林宜悉 發佈於 2024 年 02 月 25 日
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