Treating hearing loss is very good for your health! Studies show hearing aids extend life and improve quality of life. Moreover, treating hearing loss is very beneficial to brain health. Researchers are reversing symptoms of dementia and Alzheimer's Disease. Appropriate treatment works! (See the annotated references with links to the studies below this Overview.)
Chronic health problems are associated with untreated hearing loss. Nevertheless, treatments are effective. Here is a summary of health problems hearing loss is associated with:
- Early onset dementia – up to 5X greater risk [hearing aids used correctly shown to attenuate this higher risk]
- Accelerated shrinkage of brain tissue observed by MRI scans
- Psychological ‘disturbances’ are four times greater among the hearing loss
- 3X greater risk of injury from falling:
- CDC says falls are chief reason for hospitalization among seniors
- Hearing aids shown to improve balance
- Cardiovascular disease, e.g., heart attacks
- Cerebrovascular disease, e.g., strokes
- Diabetes: 21% of diabetics have hearing loss; compared to only 9% of non-diabetics have hearing loss
- Nutritional deficits are also associated with hearing loss and dementia
- Elevated levels of the neurotoxin homocysteine is linked to age related hearing loss and dementia
- Antioxidant Vitamin B supplements reduced levels of homocysteine; moreover, it prevented age related hearing loss for study participants compared to the placebo group.
The importance of routine hearing testing and accessing treatment for hearing loss is indisputable. Finally, it is very important to protect good hearing.
Treating Hearing Loss and the Brain
25-Year Study Following 3,670 People Found Wearing Hearing Aids Improved Brain Health 
Use of hearing aids when coordinated with appropriate services helps people with hearing loss keep their brain healthy longer with aging and functioning at higher levels.
This 25-year study was published in the Journal of the American Geriatrics Society. It found that people with hearing loss who used hearing aids had healthier brain functioning. People that relied on hearing aids to treat hearing loss tested as well on cognitive ability as people without any hearing loss. Moreover, study participants with hearing problems that did not use hearing aids had more rapid declines in cognitive functioning with aging. This result matched earlier research that found patients with hearing loss are up to 5 times more likely to develop dementia (see below).
This finding is very important because previous research established a link between hearing loss and dementia, accelerated shrinkage of brain tissue, and lower test scores of cognitive skills. This new research found that correctly wearing hearing aids attenuated the risk. In other words, brain health for people with no hearing loss was comparable to brain health for the people with hearing loss when they accessed hearing care treatment.
Authors of the study also concluded that hearing aid use should be coordinated with aural rehabilitation for patients to obtain optimal benefits from using hearing aids.
COMMENT: Some promoters of hearing devices are quick to say research proves wearing hearing aids keeps the brain healthy. In addition, hearing aids attenuate the risk of dementia. But researchers underscore the importance of hearing aids in conjunction with aural rehabilitation. Moreover, addressing community and social dimensions of hearing and communication is crucial for patients to obtain optimal benefit from treatment. In conclusion, treating hearing loss is ultimately a social endeavor.
This report says one-third of dementia can be prevented, and treating hearing loss helps. The first Lancet Commission on Dementia Prevention and Care, brought together 24 international experts. They reviewed existing dementia research. Finally, they provided recommendations for treating and preventing the devastating condition. In conclusion, the Commission identified nine modifiable risk factors that could “reduce the incidence of dementia or substantially delay its onset.” One of these factors is treating hearing loss in mid-life.
Proper Nutrition Can Help Prevent Age Related Hearing Loss 
Healthy nutrition plays a role in treating hearing loss. Research finds that patients with hearing loss and dementia have higher levels of the neurotoxin homocysteine. Moreover, elevated levels of homocysteine have been associated with cardiovascular and neurological conditions. But researchers have recently found it is also linked to hearing loss as well. In addition, people with elevated levels of homocysteine were 64% more likely to have hearing loss than people with lower homocysteine. Nevertheless, the antioxidant effects of folate and B vitamins is associated with decreased levels of homocysteine. In conclusion, several studies have found that folate and Vitamin B supplements lowered hearing loss.
"Evidence has continued to reveal that folate supplementation can prevent, slow, and possibly even reverse age-related hearing loss." 
Healthy Diet May Lower Risk of Hearing Loss – May 11, 2018
Researchers from Brigham and Women’s Hospital found that a healthy diet reduced acquired hearing loss in women by 30% or more. The women followed three healthy diets: The Alternate Mediterranean Diet (AMED), Dietary Approaches to Stop Hypertension (DASH), and the Alternative Healthy Eating Index-2010 (AHEI-2010). 70,966 women in the Nurses’ Health Study II were followed for 22 years. Researchers concluded that healthy diet is associated with lower risk of acquiring hearing loss.
This is one more study that reaffirms significant benefits of a healthy diet. A substantial body of research already has found eating healthy promotes better brain health and cognitive functioning. This study specifically associates healthy eating with better hearing outcomes. The hearing system is part of the nervous system.
Finally, it seems reasonable to conclude that a well balanced healthy diet improves the nervous system, brain, and hearing for both men and women. Nevertheless, this research does not suggest that other risk factors like exposure to loud sounds are any less dangerous to hearing.
Link to dementia
An 18 year study following 639 subjects as part of the Baltimore Longitudinal Study of Aging found that, “Controlling for age, medical risk factors, diabetes, hypertension, we found that people who began with hearing loss had a greater incidence of dementia.”  Dr. Frank Lin and his colleagues at Johns Hopkins point out persons with hearing loss display losses in cognitive functioning three years sooner than the general population. If hearing aid use can close that gap and delay declines in cognitive functioning among the hearing impaired, the savings to the health care system could run into the billions. [NOTE: A 25-year longitudinal study published in the Journal of the American Geriatrics Society, online October 20, 2015 - see above - found people with hearing loss that used hearing aids performed as well on tests of cognitive skills as people with no hearing loss.]
Hearing Loss Linked to Accelerated Loss of Brain Tissue
Although the brain becomes smaller with age for everyone, brain tissue shrinkage is more rapid in people with hearing loss according to the results of a study by researchers from Johns Hopkins and the National Institute on Aging. 
Psychological ‘disturbances’ are four times greater among the hearing loss as compared to the general population. Two-thirds of those with hearing loss report severe social and emotional handicaps on tests of psychological functioning. Patterns of depression seem to correlate with the progression of sensorineural hearing loss. 
Hearing Loss and Injuries from Falling
Hearing loss is associated with falling. A study led by a Johns Hopkins researcher suggests that having hearing loss triples the risk of falling for people in their 40s and later.  In addition, there is a 3-times greater risk of falling with only mild hearing loss. But the risk increases as the hearing loss increases.
Frank Lin, MD, PhD, at Johns Hopkins, and Luigi Ferrucci, MD, PhD, of the National Institute on Aging, used data from the 2001 to 2004 cycles of the National Health and Nutrition Examination Survey. “One out of three adults (age 65 and older) fall each year and falls are the leading cause of fatal and nonfatal injuries.”  Researchers believe the increased incidence of falling among patients with hearing loss stems from decreased awareness of surroundings. They also believe the mental distraction of hearing loss on cognitive functioning is a factor.
Falls Linked to Brain Injury
The Center for Disease Control has estimated that as many as 5.3 million Americans are living with a brain injury. Moreover, a significant head injury occurs about every 21 seconds. In 2010, about 2.5 million emergency department visits, hospitalizations or deaths were associated with traumatic brain injury (TBI). The primary contributing factor for TBIs among adults aged 65 and older is falls. In addition, other contributing events include concussive high pressure waves from explosions and sports-related injuries. 
Study finds evidence that using hearing aids improves balance.
Treating hearing loss helps prevent falls. Timothy E. Hullar, MD, FACS at Washington University School of Medicine in St. Louis, published a study that suggests using hearing aids may improve balance and help patients avoid injuries from falls. See the Washington University article “Hearing aids may improve balance” – December 11, 2014. The original report, “The effect of hearing aids on postural stability” was first published online, October 24, 2014. It can be found in The Laryngoscope, Volume 125, Issue 3, pages 720–723, March 2015.
A more recent study cited in the Journal of the American Medical Association found that persons with self-reported hearing loss were twice as likely to suffer accidental injuries as persons with no hearing loss. 
Heart Disease and Strokes
Low-frequency hearing loss is associated with higher occurrence of cardiovascular disease. A study, published in The Laryngoscope, also found that hearing loss correlates strongly with cerebrovascular and peripheral arterial disease. Therefore, seeking help in treating hearing loss matters to your heart. Moreover, a hearing loss finding may represent a screening test for those at risk of heart disease or stroke. In conclusion, researchers strongly recommend that patients with low-frequency hearing loss be considered at risk for cardiovascular events, and appropriate referrals considered. The finding is supported by a sizable body of data collected for more than six decades. [http://www.betterhearing.org/news/heart-disease-and-hearing-loss-linked-so-get-your-hearing-checked-world-heart-day-bhi-advises]
Cardiovascular diseases, including heart disease and stroke, cause 17.3 million deaths each year.
Diabetes and Hearing Loss
Research found hearing loss twice as common among people with diabetes compared to people with no diabetes. Among the 86 million Americans with prediabetes, hearing loss is 30% more frequent than among people with normal blood glucose. [http://www.diabetes.org/living-with-diabetes/treatment-and-care/seniors/diabetes-and-hearing-loss.html?referrer=https://www.google.com/]
 bit.ly/1RCnDHP Self-Reported Hearing Loss, Hearing Aids, and Cognitive Decline in Elderly Adults: A 25-Year Study, Helene Amieva, PhD, Journal of the American Geriatrics Society, online October 20, 2015. See also, “Hearing aids may slow mental decline in hard-of-hearing elderly” http://www.reuters.com/article/us-health-elderly-hearing-aids-idUSKCN0SU2D920151105
 Clyde Simmons, "High Homocysteine and Hearing Loss," Life Extension Magazine, April 2018.
 Auerhahn C. Daily folic acid supplementation for 3 years reduced age related hearing loss. Evid Based Nurs. 2007;10(3):88.
 “Hearing Loss Linked to Accelerated Brain Tissue Loss”, Johns Hopkins Medicine, January 22, 2014,http://www.hopkinsmedicine.org/news/media/releases/hearing_loss_linked_to_accelerated_brain_tissue_loss_
 “Quality-of-Life Changes and Hearing Impairment. A Randomized Trial,” by C.D. Mulrow et al., Annals of Internal Medicine, 1990
 “Hearing Loss and Falls Among Older Adults in the United States” by Frank R. Lin, MD, PhD and Luigi Ferrucci, MD, PhD, Archives of Internal Medicine, Volume 172, No. 4, Feb 27, 2012, pp 369 ff. See a summary at: http://www.hearingreview.com/2012/02/johns-hopkins-hearing-loss-triples-risk-for-falling-in-middle-aged-adults-and-elderly/#sthash.8QrPZuml.dpuf
 Peter Marincovich, PhD, Recognizing and evaluating head injury-associated hearing loss, January 5, 2015, http://speech-language-pathology-audiology.advanceweb.com/Hearing-Practice-Management/Features/Articles/Hearing-Loss-TBI.aspx?utm_campaign=1436897&utm_content=9567624674&utm_medium=email&utm_source=Emailvision
 Harrison W. Lin, MD; Hossein Mahboubi, MD, MPH; Neil Bhattacharyya, MD; Self-reported Hearing Difficulty and Risk of Accidental Injury in US Adults, 2007 to 2015, Published Online: March 22, 2018: 10.1001/jamaoto.2018.0039