Have you heard the word? Hearing loss causes brain tissue loss, and dramatically increases risk for dementia. But how? (The connections are fascinating.) But more importantly there are 5 simple things you can do NOW to reduce your risk for both! Or if you are a health care professional, here’s what you can share to help others avoid this devastating combination.
Several studies over the past thirty years have noted a connection between hearing loss and cognitive decline. For example in 1986 a study of 156 Alzheimer’s patients concluded that “hearing impairment may be a prognostic indicator for subsequent cognitive dysfunction.”
Three years later, another study compared 100 Alzheimer’s patients with an equal number of healthy people of the same age, sex and education. The researchers found that hearing loss was significantly higher in the Alzheimer’s group. The greater the hearing loss the greater the odds of having dementia.
But what most people are now talking about are the more recent long-term studies conducted by Frank Lin, M.D., Ph.D, at Johns Hopkins.[1]
In the longest study that tracked 639 adults for nearly12 years, Dr. Lin and his colleagues found that mild hearing loss doubled dementia risk. Moderate loss tripled risk, and people with a severe hearing impairment were five times more likely to develop dementia. Additionally, brain scans conducted during these studies showed “hearing loss may contribute to a faster rate of atrophy [tissue loss] in the brain.” Moreover, hearing loss may account for as much as 36% of dementia cases.[2]
So Why Is That? What Is The Connection?
While this is still being studied there are several good theories, and a few things investigators are quite sure about. The first idea theorizes that hearing loss precedes and somehow causes cognitive decline, and memory loss.
- Reduced auditory stimulation due to inner ear damage, results in reduced brain stimulation, leading to brain atrophy from disuse.
- Hearing loss leads to social isolation which results in reduced mental stimulation and therefore less whole brain activity and atrophy.
However:
- Both are associated with escalated shrinkage in brain structures and tissues.
- Lin notes, there could be neurodegenerative processes that are common to both the auditory pathways and other areas critical to brain function, language and memory.
Regarding the last two.
While it’s well validated that reduced auditory stimulation and social isolation can lead to other cognitive decline, there are some very interesting observations in the literature which suggest that there are also, as Dr. Lin observed underlying degenerative processes that affect both hearing and other cognitive functions simultaneously. For example:
Age is a factor both in the development of dementia and hearing loss. And five of the primary contributors to age related cognitive decline also affect structures and functions in the inner ear. These are (1) impaired blood flow, resulting in (2) reduced oxygen, (3) nutritional deficits, (4) oxidative stress – i.e. rusting or toxic exhaust at the cellular level, caused in large measure by (5) impaired metabolism and energy production in our cells tiny energy generators – our mitochondria. (When mitochondria are lacking either oxygen, glucose, or required nutrients, they produce less energy and more reactive oxygen species (ROS) or free radicals which cause oxidative stress.)
Accordingly, we know that individuals with Alzheimer’s typically have more oxygen and nutritional deficits mitochondrial dysfunction and therefore impaired metabolism or energy production, and accordingly more (ROS) or free radicals, and thus more oxidative stress in brain cells and blood vessels, leading to impaired blood flow, increased brain cell damage and death, tissue loss, “brain atrophy” and shrinkage that accompanies dementia, as noted above.
Now read this summary of one of the primary causes of hearing loss.
“Presbycusis, or age-related deterioration of hearing ability can result from loud noises… Loud noise affects metabolism in hair cells by decreasing oxygen supply and increasing energy demands. Loud noise can disrupt the flow in blood vessels that supply oxygen to hair cells, depriving these cells of nutrients needed to function and leading to cell damage through a process known as ischemia [inadequate blood supply]. At the same time, the increased stimulation due to noise forces the hair cells to be metabolically more active. The end result is that, during this period of intense stimulation, these hair cells burn through their energy reserves, resulting in the formation of reactive oxygen species (ROS). These ROS have the ability to damage proteins and lipids and can ultimately lead to death of the hair cells (Henderson 2006).[3]
(Incidentally, these “hair cells” in the Cochlea are specialized nerve cells that help translate sound waves into interpretable signals for the brain, not to be confused with hair follicles.)
So interestingly enough we see the same or similar destructive processes going on in each of these conditions – impaired blood flow, reduced nutrient and oxygen supply, increased or impaired metabolism (combined with fewer antioxidants) resulting in oxidative stress, damage to proteins, and death to cells.
Now of course this is not the only cause of hearing loss or brain cell damage.
Loud sounds also damage hair cells through direct mechanical trauma as well as secondary metabolic damage. Direct mechanical trauma typically causes immediate structural damage to cochlear hair cells and can potentially cause immediately detectable hearing loss. The metabolic effects of loud noise outlined above, however, can accumulate for days or even weeks after initial sound exposure. (Oishi 2011).[4]
Moreover, infections, various toxins, as well as trauma can adversely affect both the inner ear as well as the rest of the brain. Also the resulting inflammation and a process called “excitotoxicity,” wherein cells become overstimulated due initially to loud noises and then the excess glutamate and calcium leakage these produce, along with inadequate magnesium within the cells.[5] Excess glutamate and free radicals over time can further impair blood flow. (The Alzheimer’s drug Namenda is designed to help reduce this condition, and a new sound therapy may help as well.)
Although advancing age is said to be the most important underlying risk factor, people with heart disease, high blood pressure, diabetes and an extensive smoking history are more likely to develop hearing loss,[6], [7] as well as Alzheimer’s and other types of dementia.[8] But a quick glance will reveal that each of these disorders have either a reduced vascular, metabolic, or oxidative impact on the brain.
But, not only does excessive noise damage hearing directly, it may also increase physiologic stress, resulting in raised cortisol levels.[9] Elevated cortisol is also associated with an increased risk of hypertension, insulin resistance[10] and Alzheimer’s.[11]
Common Contributors to BOTH Hearing Loss AND Dementia
So in summary a review of related literature suggests both hearing loss and dementia seem to have the following elements in common.
- Impaired blood flow
- Reduced oxygen
- Nutritional deficits
- Oxidative stress
- Impaired metabolism and energy production
But also
- Excessive toxins in one’s diet, meds or environment
- Excess glutamate & calcium with reduced magnesium resulting in a condition of “excitotoxicity” within the cell.
- Excessive stress with high cortisol
- Excessive Inflammation
- Diabetes or insulin resistance
The Good News
This may all seem a bit overwhelming and the deck may appear to be stacked against us. However, the good news is that many of the same things that will reduce hearing loss will reduce one’s risk for Alzheimer’s and other types of dementia as well. And visa versa.
So let’s take a look at what several of these protective measures might be. I’m quite sure some will be familiar to you.
1. Improved nutrition. When I looked up nutrients that have been shown to support hearing, and reduce risk for hearing loss, I was amazed at the similarity. It was pretty much same same.
You may recall the formula I talked about in class, developed after 10 years of research by Dr. Thomas Shea at UMass-Lowell, and shown to reduce symptoms of Alzheimer’s. It contained the following ingredients NAC (N-acetyl-cysteine), Acetyl-L-carnitine, folic acid, B-12, vitamin E and SAMe. Now I invite you to go to the Life Extension Protocol to reduce Hearing Loss, Section 7, and you’ll see the first thing they talk about is the importance of antioxidants to control oxidative stress. And the first one mentioned is NAC. Note:
- NAC… increases the production of glutathione, one of the most prevalent antioxidants in the body (Kopke 2007). NAC has been studied as a potential therapeutic agent to protect hair cells from damage due to excessive noise as well. A 2011 study on military recruits found that NAC was able to protect the cochlea from damage due to noise from firing a gun in an enclosed space (Lindblad 2011). Animal studies have also found that NAC has a protective effect against continuous loud noises (Lorito 2006; Bielefeld 2007) as well as impulse noise (Kopke 2005). Another animal study showed that NAC may reduce noise-induced hearing loss even when administered after exposure to dangerous levels of noise (Coleman 2007).
- Acetyl-L-carnitine “…is able to protect the cochlea from both continuous and impulse noise damage as well as prevent loss of hair cells (Kopke 2002; Kopke 2005). Acetyl-L-carnitine was also found to reduce mutations in mitochondrial DNA, suggesting that it could prevent not only noise-induced hearing loss, but also age-related hearing loss (Seidman 2000). Much like NAC, acetyl-L-carnitine appears to be effective even when administered after exposure to loud noise(s) (Coleman 2007; Du 2012). In one animal study, acetyl-L-carnitine was shown to protect against ototoxicity induced by the chemotherapeutic drug cisplatin (Gunes 2011).
- SAMe is not mentioned in this protocol, likely because it is relatively new as a supplement, and there hasn’t been much, if any research done on it in relation to hearing loss. But it is a co-factor of glutathione and a primary protector of mitochondrial DNA.
A little further down they talk about the importance of certain vitamins noting:
- Vitamins A and E have shown significant protective effects (Hou 2003; Ahn 2005).
- Folate and Vitamin B-12 help reduce levels of homocysteine, a potentially toxic compound found in the body. Elevated homocysteine levels are linked to an increased risk of hearing problems (Gok 2004; Gopinath 2010)…Researchers have found that patients with low levels of folate in their blood are more likely to develop hearing loss (Gok 2004; Lasisi 2010; Gopinath 2010), and that low vitamin B12 levels are associated with hearing loss (Gok 2004) and tinnitus (Shemesh 1993).
* homocysteine is also a major contributor to Alzheimer’s
And minerals, especially magnesium. Note it’s effects:
- Magnesium is known to help expand blood vessels and improve circulation; it also helps control the release of glutamate, one of the major contributors to noise-induced hearing loss (Le Prell 2011)… A combination of magnesium and other antioxidants may synergistically prevent hearing loss, potentially because magnesium’s ability to increase blood flow also helps transport the protective antioxidants (Le Prell 2011)…supplementation (122 mg daily for ten days) reduced noise-induced hearing loss in men aged 16-37 years (Attias 2004). Studies have also found… magnesium supplementation may be beneficial for other types of hearing loss, such as sudden sensorineural hearing loss (Gordin 2002; Coates 2010).
The protocol goes on to review research with zinc, melotonin, Ginkgo Biloba, CoQ10, Omega-3 fatty acids, and taurine. All of which have been shown to help maintain a healthy brain and stave off dementia.
This quick lit review helps us see why a Mediterranean type diet, shown to help protect against dementia may also help to protect against hearing loss. The vegetables, beans, nuts and seeds in such a diet would help to provide the folate, NAC, Vitamin E as well as magnesium and zinc needed to protect hearing. And the fish or chicken, and egg yolk would help supply the Omega-3, B-12, NAC, carnitine and taurine.
2. Physical Activity (moderate exercise) has many benefits for the brain, and can help to protect hearing by improving metabolism, reducing diabetes and high blood sugar, improving blood, nutrient and oxygen flow to the inner ear, as well as the rest of the brain.
3. Avoid Loud Noise, or use ear plugs. It’s abundantly clear that loud noisy environments can have a serious impact on hearing. Both immediately and over time as we age.
4. Hearing aids. Two new studies revealed in 2015 showed that newer models of hearing aids can be very helpful in reducing the stress and social withdrawal associated with hearing loss, which allow for more appropriate and healthy brain stimulation. Accordingly these have been shown to significantly mitigate the risk for dementia due to hearing loss.[13]
5. Nutritional Supplements. Since it’s often hard to get all the nutrients we need, especially as we age. As noted In our study with Alzheimer’s patients.[14] There are some high quality nutritional supplements that may make a significant difference here. And the two that appear most in line with the research compiled by Life Extension Foundation, that address multiple risk factors for both of these disorders are Perceptiv™,[15] and the drink mix Memoryze™.[16]
(If you are interested in trying either of these just email me: David at DavidRJL@aol.com or give me a call at 801-529-8238,
and I will tell you were you can obtain either at the best price.)
Again we are back to the idea that a simple brain healthy diet and lifestyle may help to reduce ones risk for both of these disorders, as well as hypertension and diabetes, and a host of related condition.
Although nearly 27 million Americans age 50 and older have hearing loss, only one in seven do anything about it. If you think your hearing or that of a loved one has diminished, it’s worth making an appointment with an audiologist for a hearing check, especially when there now appear to be several things that can be done to reduce not only the hearing loss, but the much greater dementia risk as well.
References
[1] Hearing Loss Linked to Accelerated Brain Tissue Loss. Johns Hopkins Medicine. [Online] January 22, 2014. http://www.hopkinsmedicine.org/health/healthy_aging/healthy_body/the-hidden-risks-of-hearing-loss
[2] https://www.beltone.com/hearing-health/alzheimers-and-hearing-loss.aspx
[3] http://www.lifeextension.com/protocols/eye-ear/tinnitus/page-04
[4] Oishi N and Schacht J. Emerging Treatments for Noise-Induced Hearing Loss. Expert Opinion on Emerging Drugs, 2011; 16(2) 235-245
[5] Pujol R and Puel JL.Excitotoxicity, Synaptic Repair and Functional Recovery in the Mammalian Cochlea: A Review of Recent Findings. Annals of the New York Academy of Sciences, 1999.
[6] Helzner EP, Cauley JA, et al. Race and Sex Differences in Age-related Hearing Loss: the Health, Aging and Body Composition Study. J Am Geriatr. Soc, 2005; 53(12): 2119-27.
[7] Bielefeld EC, Tanaka C, Chen GD, et al. Age-Related Hearing Loss: Is It a Preventable Condition? [In eng] Hear Res. 2010 Jun 1; 264(1-2): 98-107.
[8] See http://www.thelancet.com/journals/laneur/article/PIIS1474-4422(14)70136-X/abstract
[9] Seidman MD and Standring RT. Noise and Quality of Life. International Journal of Environmental Research and Public Health, 2010; 7: 3730-3738.
[10] Tsigos C and Chrousos GP.Hypothalamic-pituitary-adrenal Axis, Neuroendocrine Factors, and Stress. Journal of P. Etiology of sychosomatic Research, 2002; 53: 865-871.
[11] Click Stress and Depression on the brain quadrant to the right.
[12] See homocysteine
[13] Amieva H, Ouvrard C, Giulioli C, et al. (2015) Self-Reported Hearing Loss, Hearing Aids, and Cognitive Decline in Elderly Adults: A 25-Year Study. Journal of the American Geriatrics Society, Oct;63(10):2099-104. doi: 10.1111/jgs.13649. http://www.ncbi.nlm.nih.gov/pubmed/26480972
Hearing Aids Improve Memory, Attention; Most People Have Hearing Loss in their Lifetime. Feb 1, 2016, University of Texas. http://news.utep.edu/?p=32076
[14] Remington, R, Bechtel C, Larsen D, et al (2015) A Phase II Randomized Clinical Trial of a Nutritional Formulation for Cognition and Mood in Alzheimer’s Disease. J Alzheimers Dis. 2015;45(2):395-405. doi: 10.3233/JAD-142499.
http://www.ncbi.nlm.nih.gov/pubmed/25589719?dopt=Abstract
[15] See http://4abettermemory.com/memory/a-faster-way-to-memory-recovery/
[16] See http://4abettermemory.com/memory/a-faster-way-to-memory-recovery/
If you enjoyed this article, please consider sharing it!
Prevention Strategies 
