Hearing loss increases the risk of dementia
Individuals with moderate to severe hearing loss are up to 5 times as likely to develop dementia. The risk of developing dementia doubles for older adults with mild hearing loss, and triples for those with moderate hearing loss. And for those with severe hearing loss, the risk is five times that of someone who does not suffer hearing loss. Notably, the Lancet study also found that of nine potential risk factors for developing dementia, hearing loss was the highest at nine percent.
There is a lot of research showing a correlation, but it is hard to say at this particular point that there is a causal relationship. this means it is hard to say that hearing loss causes dementia. There are ways in which hearing loss and dementia can be linked.
Possible relationships between hearing loss and dementia
Hearing loss may cause brain changes
First, it is possible that hearing loss causes brain changes that raise the risk of dementia. A brain-imaging study found that areas of the brain not normally involved in language processing become activated in response to speech in people with hearing loss. This effect was seen even in healthy young adults with mild hearing loss, suggesting that brain changes which may increase dementia risk start soon after the onset of hearing damage.
A separate imaging study where brain changes were tracked in 126 people for up to 10 years found that those with hearing impairment had accelerated rates of brain atrophy, including in areas involved in memory. These studies suggest that it may be necessary to treat the hearing loss before significant brain shrinkage occurs in order to mitigate dementia risk. When the part of the brain related to hearing becomes inactive, it results in tissue loss and changes in brain structure—creating the first link between hearing loss and Alzheimer’s disease.
Shrinkage of brain tissue is fast-tracked for those with hearing loss, with accelerated rates of brain atrophy compared to those with normal hearing. Shrinkage of brain tissue for those with hearing loss was most prevalent in regions of the brain responsible for processing sound and speech, including the superior, middle, and inferior temporal gyri.
Possible brain overload?
Second, there could be brain overload. An “overwhelmed” brain creates the second link between hearing loss and dementia. When it’s difficult to hear, the brain must work overtime just to understand what people are saying. Straining to hear all day, every day, depletes a person’s mental energy and steals brainpower needed for other crucial functions like remembering, thinking, and acting. This can further set the stage for Alzheimer’s, dementia and other cognitive disorders.
Social isolation from hearing loss and Alzheimer's
The third link between hearing loss and Alzheimer’s is social isolation. A study by The National Council on the Aging (NCOA) of 2,300 hearing-impaired adults found that people with untreated hearing loss are more likely to experience loneliness, worry, depression, anxiety, and paranoia—and are less likely to join organized and casual social activities. When a person withdraws from life, their risk for dementia intensifies. People with hearing loss may not be confident in responding or re-acting appropriately and may choose to disengage from conversations. As a person with hearing impairment withdraws from social engagement, there is also a reduction in the amount of cognitive function necessary to assess and interact with his or her environment. This may impact executive function ability (ability of the brain to form judgment and make decisions).
If a loved one is showing signs of dementia, help them get their hearing checked sooner than later. Sometimes, undiagnosed hearing loss symptoms are thought to be Alzheimer’s symptoms when they’re really not.
Common cause between hearing loss and dementia
Fourth, it is possible that hearing loss and dementia share a common cause. There is clearly a strong association between the two, though we haven't been able to determine causality. For instance, the Lancet study found that central hearing loss could be a prodromal symptom of Alzheimer's disease, causing impaired speech perception, especially in the presence of competing sounds; however, it likely does not contribute to the high prevalence of dementia, as it occurs in only two percent of patients with Alzheimer's disease. Statistically, there is a possibility that hearing loss and dementia share a common cause, but that chance is very small and not very likely.
How hearing aids can help
Numerous studies show that hearing aids not only improve a person’s hearing—they also help preserve a person’s independence, mental abilities, emotional and physical health. Hearing aids also help with the person's work, home, and social lives. A full, happy life keeps the brain active. Early identification and treatment of a potential hearing loss helps minimize risks later in life. Current research affirms the connection between hearing aid use and reduction in cognitive decline, particularly in the area of working memory. In some instances, hearing aid use is the one controllable and effective action a person can take to help reduce cognitive decline.
