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Hearing Loss Linked to Dementia

A Cautionary Tale

Mounting evidence has established a  strong link between untreated hearing loss and diminished cognitive function, including dementia. Studies also link untreated hearing loss to other medical and emotional problems, including depression.

This is a cautionary tale, but a light shines brightly to guide our passage away from danger: Hearing Loss Can End Badly—but we have options!

First, the bad news. Mounting evidence has established a strong link between untreated hearing loss (HL) and diminished cognitive function, accelerated mental decline, rapid rates of brain tissue loss, and other disabling conditions, such as dementia and Alzheimer’s disease. People who don’t hear well tend to withdraw from social activities, and that can lead to depression and early mortality.

The link between HL and dementia is reinforced by statistical and brain scan studies from hearing and social neuroscience research, and backed by compelling theories for how HL promotes dementia.

Dr. Frank Lin from John Hopkins Medicine has identified three primary pathways to dementia and other bad health outcomes:

  1. HL increases the cognitive load on the brain. Struggling to understand speech causes the brain to focus on sound processing at the expense of memory, thinking, and learning processes. Robbing Peter to pay Paul leads to a cascade of bad consequences, leaving seniors vulnerable to dementia and Alzheimer’s disease.
  2. Even mild HL hastens brain tissue loss, and seniors with untreated hearing problems are much more susceptible to brain tissue loss and other unwanted brain structural changes than seniors with normal hearing. This is significant because the brain tissue loss occurs where memory and sensory integration are processed, causing a negative feedback loop that leaves seniors vulnerable to dementia.
  3. People who can’t hear well tend to avoid social engagement. This puts them at a higher risk for becoming socially isolated, lonely, and depressed—and that exposes them to a perfect storm for developing dementia and early death.

Now the good news: new research just published in the Journal of the American Geriatrics Society by researchers at the French National Institute for Health and Medical Research in Bordeaux, France found that hearing aids reduce the threat of accelerated cognitive decline. The Bordeaux study revealed that elderly people with HL who used hearing aids were spared the augmented levels of cognitive decline suffered by others with HL who didn’t use hearing aids.

Social neuroscience research found similar results

Dr. Cacioppo is the Director of the Center for Cognitive & Social Neuroscience and Chair of the Social Psychology Program at the University of Chicago. Decades of research inform the doctor that we are social by design. That means we are hard wired to connect with others. In fact, our need for social interaction is as fundamental as our need for food and water because the consequent social behaviors helped us survive & reproduce.

Highlights from social neuroscience research:

  • Socially connected people are more likely to have good physical health and psychological well-being.
  • People with strong social networks generally live longer. They also have lower rates of anxiety and depression.
  • Forming strong social bonds creates a positive feedback loop of social, emotional and physical well-being.
  • Conversely, lack of social bonding often contributes to a negative feedback loop of isolation, deep loneliness, and antisocial behavior, often leading to bad health outcomes for aging adults, including depression and dementia!

But you can’t connect with people if you can’t hear them, so it is vitally important that hearing and communication problems aren’t keeping you from a socially rewarding life.The bottom line? Hearing empowers social health and social health empower life!

See our Brochure on Hearing Loss and Dementia, here

 

Breaking News - Hearing Aids prevent Dementia study

 

Hearing Loss and Dementia

The Problem

An increasing number of independent scientific studies are showing strong evidence that hearing loss is more than just a nuisance of aging. The message is disturbing: people who experience hearing loss as they age may also have a significantly higher risk of developing cognitive disorders, including dementia. Cognitive function is an intellectual process that allows us to become aware of, perceive, or comprehend ideas. It involves all aspects of perception, thinking, reasoning, and memory.

The Evidence

A 2011 study (Hearing Loss and Incident dementia) was conducted by researchers at Johns Hopkins University School of Medicine in Baltimore in partnership with the National Institute on Aging. Dr. Frank Lin and others found that older adults with hearing loss were more likely to develop cognitive problems than others who retained normal hearing as they aged, and the risk of developing dementia increased with the degree of hearing loss. The study found that people with severe hearing loss were five times more likely to develop cognitive problems, and even mild hearing loss doubled the risk for serious cognitive impairment Las Vegas.

In a follow-up study (Hearing Loss and Cognitive Decline in Older Adults, 2013) Dr. Lin and colleagues substantiated that older adults with hearing loss were more likely to develop thinking and memory problems than older adults with normal hearing, and the degree of cognitive degeneration was directly related to the amount of hearing loss. The study found that cognitive capabilities for those with hearing loss declined 30 to 40 percent faster than they did for a group with normal hearing. According to Dr. Lin, The results of the study should prompt an effort to make age-related hearing loss a public health priority.

Other studies indicate that hearing loss accelerates atrophy in auditory areas of the brain, making it more difficult for older adults to comprehend speech. “Your hearing ability directly affects how the brain processes sounds, including speech,” says Dr. Jonathon Peelle, PhD, research associate in the Department of Neurology at the University of Pennsylvania. “Preserving your hearing doesn’t only protect your ears, but also helps your brain perform at its best.”

Pathways to Dementia

Although the studies could not determine a direct link from hearing loss to cognitive degeneration, researchers proposed several pathways that could lead from hearing loss to dementia, and these are summarized in the figure. The first pathway (gold arrows) is known as “cognitive load.” As hearing loss progresses, the brain must devote greater resources to auditory processing (speech and sound) at the detriment of thinking and memory. Another pathway (blue arrows) leads from hearing loss to social isolation, prompted by increasing communication difficulties. Social isolation has been well established in previous research as a risk factor for cognitive decline. A third pathway (green arrows) is known as auditory deprivation. When the hearing nerves and regions of the brain responsible for hearing are deprived of sound, they atrophy, a process that can accelerate the onset of dementia. An argument could be made that some other, yet-to-be-determined physiologic factor may serve as a common cause for both hearing loss and dementia, but many researchers agree that there is strong evidence to support a causative link from hearing loss to significant cognitive decline in older adults.

Epilogue

Although we don’t have clear evidence that hearing aids, cochlear implants and other rehabilitative measures will reduce or prevent cognitive degeneration, many clinical researchers are convinced that these interventions improve the lives of their patients. As Dr. Lin noted, “they are able to engage again: they
are no longer isolated.”  So…there are no downsides to treatment…but there may be serious downsides to letting hearing loss go full course!