Doc's Journal at AberdeenAudiology.com

Researchers Link Dementia and Hearing Loss

A recent study from the Baltimore Longitudinal Study on Aging, published in the Archives of Neurology suggests a strong link between hearing loss and dementia.

Frank R. Lin, M.D., Ph.D. and his team studied associations between hearing loss and dementia. 639 initially dementia-free adults underwent audiometric testing between 1990 and 1994 and were followed up for the development of dementia or Alzheimer's disease through May 31, 2008. The statistical analysis indicated that among individuals older than 60 years, the researchers estimated that more than one-third of the risk for incident all-cause dementia was associated with hearing loss.

In interviews since the study was published, Dr. Lin has speculated that hearing loss may be causally related to dementia "through exhaustion of cognitive reserve, social isolation, environmental deafferentation, or a combination of these pathways."

That is certainly on possibility. In my opinion, the more likely possibility is that the decrease in sensory input to the brain causes certain cognitive abilities to atrophy.

The next question, logically, is "will using hearing aids help to stave off dementia?" If my hypothesis is correct, then yes, hearing aids would theoretically help stave off the symptoms of dementia. However, no research has been done on this theory as of yet.

Time will tell, but in the mean time, this is just one more reason to take care of your hearing health.

Reference: Medscape.com

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Hearing Loss and Hearing Aids for Young and Old Discussed on The Today Show

Visit msnbc.com for breaking news, world news, and news about the economy

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File Under: "You Get What You Pay For"

I'm often asked why digital hearing aids are so expensive when there are advertisements on television and in magazines for "personal sound amplifying devices" that promise that you will "hear better than ever before!" for only $29.99 [and if you act now, get a second device free!]. While always taking the time to explain in great detail as to why "you get what you pay for", I've never seen it explained quite as well as Dr. Judith Albrecht did in the recent member newsletter from the Pennsylvania Academy of Audiology.

Dr. Albrecht, operating under the assumption that pictures do more than words, reprinted a graph illustrating how these devices under-amplify the high frequencies, the range of sounds that are essential for speech understanding, while over-amplifying low-frequency sounds. The over-amplification of low frequency sounds has a negative effect on benefit, making the world sound too noisy and masking valuable speech content in the higher pitches.

In her graphic, re-re-printed below [click to enlarge], the o--o--o line represents a patient's thresholds which are very representative of the average sensorineural hearing loss that most patients suffer from. Anything below that line is inaudible to this patient, while anything above it is audible. At the other end of the loudness spectrum, the U--U--U line represents the loudest sound the patient can tolerate and so anything near that line or over it will be perceived as uncomfortably loud.

 

As you can see, the custom digital hearing aid does a much better job of making the high-pitch sounds --again, so necessary for improved speech intelligibility-- audible while preventing sounds from getting too close to the patient's tolerance levels.

If the hearing loss that almost every patient has, the sensorineural hearing loss, were easily rectified by just making sounds louder, then the the cheap little $29.99 amplifier would be the perfect solution. Unfortunately that's not the case, but fortunately, there are plenty of audiologists nearby waiting to be of service to you.

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Noise Levels at the Stanley Cup Playoffs

Similar to the Phillies world championship runs in 2008 and 2009 [2010 too?], the Flyers are taking Philadelphia by storm. Like any good fan base, Flyer fans are making things loud for the visiting Chicago Blackhawks. As a matter of fact, NHL.com published sound level readings for Game 3 at the Wachovia Center in South Philly.

When Danny Briere scored a power play goal in the first period, the noise reached 112 dB, the upper range of human tolerance without inducing pain and 114 dB was reached when Claude Giroux scored the game winning goal in overtime.  These "official" measurements are consistent with the informal measurements I made myself on my smartphone while at the Eastern Conference semifinal win over the Montreal Canadiens.

For the most part, it is best to avoid environments that loud in order to avoid causing damage to your ears. In instances when you can't avoid situations like that, it is best to wear hearing protection such as custom made ear plugs, generic ear plugs, or circumaural headphones. You may recall, when Drew Brees won the Super Bowl with the New Orleans Saints, his young son was seen on the field during the post-game celebration wearing hearing protection.

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Be Wary of What's In Your Medicine Cabinet [Part I]

The following is the first of a two-part entry examining common medications and their effects on hearing and balance.  Before altering or discontinuing the use of any prescribed medication, consult your physician.

In recent decades, more and more medications are being prescribed to more and more people.  For the most part, today's pharmaceuticals often allow people to live longer and with a higher quality-of-life.  However, these medications do not come without strings attached.  As a matter of fact, at times, their side effects may cause other health issues, in particular, hearing and/or balance disturbances.

Somewhere, in every physician's office is a large thick book that makes your average dictionary look like a pamphlet: the Physician's Desk Reference, or PDR for short.  The PDR contains a description of countless medications including their uses, dosages, and of course side effects.  Of the total number of side effects listed in the PDR, over 300 can influence one's hearing and/or balance.  Here are some examples of those 300-plus side effects:

• "hearing loss, reversible"
• "hyperacusis"
• "tinnitus"
• "ears, roaring in"
• "vertigo"
• "capillary fragility"
• "feeling, intoxicated"

Obviously, some of those side effects relate directly to hearing and balance, while others are less obvious.  For instance, capillary fragility, while not necessarily directly related to hearing and balance, can prevent the sensory cells in the inner ear from receiving the nutrients and blood supply they need, which leads to their atrophy or cell death.  Those issues will in turn causes hearing loss and/or dizziness, perhaps permanently.

In Part II of this series, we'll examine what types of medications can cause hearing and/or balance disturbances.  You may be surprised to find out that many are commonly used and prescribed.

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The Nature of Hearing Loss and the Fundamentals of Proper Amplification (Part III)

In Parts I and II of this series, we discussed the symptoms of sensorineural hearing loss and the reasons behind those symptoms. For Part III, we’ll take a look at why these symptoms are associated with sensorineural hearing loss – also known as “nerve deafness”, which you will soon see, is a bit of a misnomer.

Our ears have three parts: the Outer, the Middle, and the Inner. Sensorineural hearing loss, the most common type of hearing loss in adults, is caused by pathologies in the inner ear. The inner ear is shaped very similar to a snail shell, wound in a circle. Inside the “shell” is a membrane that runs the length of the inner ear, or cochlea. On this membrane are thousands upon thousands of microscopic sensory cells, sometimes nicknamed “hair cells” due to the tiny cilia perched on top of them.

Any particular point on the membrane inside the cochlea is tuned to a particular pitch. When a sound enters the Inner ear after passing through the Outer and Middle ears, it vibrates the membrane, which in turn stimulates the sensory or hair cells [at right, click to enlarge]. When these cells are stimulated, they convert the acoustic signal into an electrical signal, which travels up the auditory nerve fibers they are attached to, all the way to the brainstem and auditory cortex in the brain.

It is these loss of sensory cells in the inner ear that are the greatest contributor to sensorineural hearing loss (for this reason, "nerve deafness" is a very misunderstood term) and the cells nestled on the portion of the membrane tuned to higher pitches are the first to go.

To conclude this series, Part IV will cover the basics of proper amplification because contrary to what you may have been told, hearing aids can and do help patients with "nerve deafness". As a matter of fact, proper amplification benefits millions of people every day.

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The Nature of Hearing Loss and the Fundamentals of Proper Amplification (Part II)

In Part I, we discussed the typical symptoms of the most common form of hearing loss, sensorineural hearing loss. As you may recall, in most cases, but not all, vowels (a, e, i, o, and u) remain audible to the patient, but consonants (s, f, t, v, etc.) become inaudible. This is because those two types of sounds of speech have different pitch ranges.

Vowels are predominantly strong and low-pitched, while consonants are usually weaker and higher in pitch. Also, consonants are the sounds that give speech its clarity, while vowels give speech its rhythm, quality, tone, and inflection.

Here’s where the irony comes in… When a person suffers from sensorineural hearing loss, it typically affects the higher pitches of their hearing range more than the lower pitches. To the right is a diagram [click to enlarge] of a hypothetical patient’s hearing thresholds by frequency or pitch (x-axis) and intensity (y-axis). It’s also possible to plot other environmental or speech sounds on the graph and so anything above the red and blue line is theoretically inaudible to the hypothetical patient, while anything below is audible. This is why patients will often observe that they can hear nearly everyone, but yet understanding what is being said is another story altogether.

In Part III, we’ll discuss why the higher pitches of someone’s hearing are affected more than lower pitches and in Part IV, the basics of proper amplification.

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The Nature of Hearing Loss and the Fundamentals of Proper Amplification (Part I)

Take a poll of audiologists about the observation or complaint they most often receive from patients and I’m willing to wager that the hands-down, clear-and-away, favorite would be something to the effect of “I hear just fine, but speech isn’t clear.” Variations would include “Everyone mumbles” and “I just can’t make out the words”.

There’s a reason for all of this perceived mumbling, and that is the nature of sensorineural hearing loss, the most common form of hearing loss. Often referred to as nerve deafness, sensorineural hearing loss occurs in the inner ear, the cochlea, and is typically non-reversible by medicine or surgery. The causes are varied, but the leading ones are presbycusis (age-related), ototoxicity (drug interactions), or excessive noise exposure.

However, no matter what the cause of sensorineural hearing loss, the effect is often the same – the vowels of speech remain audible [a, e, i, o, u], while the consonants of speech [s, f, t, b, etc.] become inaudible.

To use a real life example of how this can affect one’s daily conversations, imagine printed text without many of the consonants. For instance, try and decipher the following question:

"Wi__ __e __illie_ wi_ __e Wor__ _erie_ agai_ __i_ _ea_?"

Before I reveal the true identity of that sentence, let me demonstrate what context can do to help someone with hearing loss “fill in the blanks” on an auditory perception level. Let’s say I showed you these two images before giving you the sentence: