Hearing Loss And Dementia: The Silent Connection
By David Steen Martin
Hearing loss and Dementia are more common as you get older. The latest research shows that’s no coincidence. The two are linked.
Scientists are finding more and more evidence that trouble with hearing makes you more likely to go on to have dementia, a condition
marked by memory loss and trouble with thinking, problem-solving, and other mental tasks.
That doesn’t mean that people with hearing loss (about two-thirds of adults over 70) are guaranteed to have dementia – simply that
the odds are higher. There may be things you can do to lower your chances for mental decline, even if you start to have trouble
hearing.
What’s The Link?
Scientists have found that a person’s chances for mental decline seem to go up the worse their hearing problems are. In one study, mild, moderate, and severe hearing loss made the odds of dementia 2, 3, and 5 times higher over the following 10-plus years. And it seems to happen faster. Studies of older adults who had lost some hearing found that they had mental decline 30%-40% faster, on average. Looked at another way, they had the same mental decline in 7.7 years, on average, as someone with normal hearing showed in 10.9 years. Researchers don’t know for sure how the two conditions are connected. Frank Lin, MD, PhD, of Johns Hopkins University, says three things may be involved:
- People with hearing loss tend to feel isolated, since it’s hard to join in conversations or be social with others when you can’t hear. Some research has shown a link between feeling lonely or isolated and dementia. So hearing loss may make mental decline happen faster than it would otherwise.
- Your brain has to work harder to process sound if you don’t hear well. That may take away resources that it could use for other important activities.
- If your ears can no longer pick up on as many sounds, your hearing nerves will send fewer signals to your brain. As a result, the brain declines.
“It’s likely a combination of all three,” says Lin, who has done much of the research on the connection between the conditions.
Understanding The Global Impact
(By Kelly Wolfgang: Hearing Loss and Dementia: Breakthrough Research Seeks Causal Link)
(The Hearing Journal: September 2019 – Volume 72 – Issue 9
doi: 10.1097/01. HJ.0000582420.42570.de
Approximately 30 percent of adults aged 65 and older and 55 percent older than 80 years show some degree of hearing loss. The number of people affected by age-related hearing loss is estimated to grow to 580 million worldwide by 2050. In 2015, 47 million people worldwide were living with dementia, amassing a global cost of $818 billion, according to a study published in The Lancet Commissions (Lancet. 2017 Dec 16;390[10113]:2673-2734). By 2050, when the proportion of people older than 60 years will double, accounting for 21 percent of the projected global population, the number of those living with dementia is expected to triple, costing nearly $2 trillion. 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. In addition, recent research has found that shrinkage of brain tissue is fast-tracked for those with hearing loss, with accelerated rates of brain atrophy compared to those with normal hearing. Overall, those with hearing loss were found to have lost more than an additional cubic centimetre of brain tissue each year compared with those without impaired 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. Common symptoms of both dementia and hearing loss align, including confusion during conversation, changes in methods of communicating, difficulty completing everyday tasks, and feelings of fatigue or stress. As a result, hearing loss can be misdiagnosed as dementia or make the symptoms of dementia appear worse, and research has found that hearing aid use was positively associated with episodic memory scores, with a potential mitigating effect on the trajectories of cognitive decline later in life. Despite correlational evidence between the two conditions, work remains to identify causal factors to link hearing loss and dementia.
Correlation Between Hearing Loss & Dementia
Though the reason for the correlation isn’t completely understood, several theories exist. It may be that the increased cognitive load the brain experiences when trying to hear properly taxes the resources that would otherwise be available for memory and concentration. Alternatively, a decrease in the brain’s “gray matter” may lead to a shrinkage in brain cells and a resulting inability to process sound. Another factor may be the social isolation many individuals with hearing loss experience; this lack of socialization has been shown to accelerate cognitive decline and dementia.
Hearing Aids
Whatever the reason, one thing is clear: hearing aids can help. Studies show that patients who treat their hearing loss with hearing devices reduce their odds of cognitive decline and, at the very least, delay the onset of dementia. Early detection is key! If you are experiencing hearing loss, it’s best to seek treatment as soon as possible in order to avoid mental deterioration. Even if you are unaware of a problem, schedule a hearing evaluation in order to make sure. Because symptoms develop slowly, many patients adjust to gradual changes in hearing without realizing there is anything wrong.