There have been a lot of articles released on the relationship between hearing loss and dementia, most recently, this December 2019
New York Times Article, written by Jane Brody, “For Better Brain Health, Preserve Your Hearing” which highlights the importance of hearing testing and wearing hearing aids if you have a hearing loss. Let’s dive into some of the theories behind the relationship between hearing loss and dementia.
Brain cell stimulation.
There is a theory that if you are not adequately stimulating the brain with auditory input, the brain cells responsible for processing sound can shrink. This is supported by a study from Dr. Frank Lin at Johns Hopkins and the National Institute on Aging (2014). Lin and his colleagues gave an MRI to 126 participants every year for ten years, some with normal hearing, and some with at least a mild hearing loss. The results of the study showed that those individuals with impaired hearing, lost “an additional cubic centimeter of brain tissue each year compared to those with normal hearing.” (Lin, 2014)
Social isolation.
In the field of gerontology there has been many studies supporting the theory that social isolation is one of the top predictors for morbidity and mortality in older adults. There was an amazing Ted talk by Susan Pinker, who is a medical psychologist about how the secret to living longer may be your social life. But why? The research suggests that socially isolated people have an increased upregulation of pro- inflammatory genes and increased inflammation, which causes negative health effects in the body and stimulates the aging process (Cacioppo, 2011; Cole et. Al., 2007)
The final link between hearing loss and dementia is cognitive load.
According to Kahneman (1973), each individual has a pool of cognitive resources for thinking, memory, and planning. As we age, we can lose some of these resources because the brain shrinks in volume (Peters, 2006). If you have a hearing loss, and decreased cognitive resources, this can overwhelm the brain because it is not receiving the proper input from the ears and it has to work harder to process that signal. Studies have shown that the brain will actually re allocate resources that are meant for other processes such as thinking, memory or planning, in order help process speech, and in the end that could compromise other brain functions such as short term and long term memory.
What should I take from the research?
Dr. Frank Lin (2014) suggests that
“"If you want to address hearing loss well, you want to do it sooner rather than later. If hearing loss is potentially contributing to these differences we're seeing on MRI, you want to treat it before these brain structural changes take place."
The way that I interpret this is three-fold:
1) Get your hearing tested as soon as you suspect you have a hearing loss and for sure by the age of 60
2) If you have a hearing loss, get fit with hearing aids sooner rather than later, before those brain structural changes take place
3) Stay engaged, a recent Harvard Health article revealed that people who have strong social connections tend to live longer and healthier lives.