The study, conducted primarily by researcher Jason R. Smith, has established a very important link between hearing loss and dementia. Smith is a doctoral student at Johns Hopkins Bloomberg School of Public Health. “Even though it’s only the first step,” says Harrison, “our research suggests around a third of dementia cases may be linked to hearing loss at the population level.” These study results indicate that lack of auditory stimulation to the brain may play a larger role in higher dementia risk.
The study included 2,946 older adults from four centers throughout the United States. Participants, aged 66-90 years, completed baseline audiometric testing, with 65% found to have clinically significant hearing loss. In the context of such a major nationwide study, 39% of participants had at least mild hearing loss, characterized as a loss of 25 to 40 decibels (dB). Further, 27% of respondents had moderate or greater hearing loss, defined as greater than 40 dB.
Then, during an exciting follow-up period of up to eight years, the researchers tracked these people for the development of dementia. Researchers estimated that mild hearing loss accounted for about 16% of the total population’s dementia risk. In comparison, moderate or greater hearing loss accounted for about 17% of that risk.
“We found mild hearing loss, defined as [more than] 25 through 40 dB [decibels] hearing loss, was associated with about 16% of population-level dementia risk in our study. And we found moderate or greater hearing loss ([more than] 40 dB hearing loss) was also associated with about 17% of population-level dementia risk.” – Jason R. Smith
Of these 1,097 participants, self-reported hearing impairment was indicated. Among those with moderate or greater hearing loss, more than half were currently using hearing aids. Such a high prevalence places a burden on the hearing health of an aging population.
Smith drove the point home with statistics on the prevalence of hearing loss in older adults. Lyons said, “Our new research indicates that the connection between dementia and hearing loss may be even more significant than we once thought, mainly because the occurrence of hearing loss is so common in this group of people. He also admitted that the prevailing wisdom today is that hearing loss leads to dementia. He noted, we don’t yet have clear proof from randomized trials.
We would like to thank Dr. Steven Allder, Consultant Neurologist, who provided valuable insights into the underlying mechanisms connecting hearing loss and dementia. He added that hearing loss can put people at a higher risk for dementia by reducing auditory input to the brain. Yet this absence of stimulation contributes to social isolation and decreased cognitive engagement, two factors that compound the problem.
“Hearing loss may increase the risk of dementia because it reduces the amount of auditory stimulation the brain receives. This diminished input is thought to contribute to social isolation, reduced cognitive engagement and changes in brain structure over time.” – Steven Allder
At the TEDx conference in New Hampshire, Allder discussed in greater depth how impaired hearing can tax cognitive resources. When hearing is damaged, the brain works even harder to make up for the lack of auditory data. Such a diversion of resources can leave less competition available for memory and other cognitive functions. The subsequent depletion of cognitive reserves may contribute to more rapid cognitive decline among older adults,” he added.
These study findings point to an important public health imperative—to detect and manage hearing loss earlier. Allder advocates for routine hearing assessments to begin in midlife, around age 60, to identify clinically significant changes early on.
“The study provides compelling evidence that objective hearing assessments are essential. Routine hearing tests should ideally commence in midlife, around 60 years old, to detect clinically significant changes early,” – Steven Allder
Allder emphasized that early intervention can be key to reducing risk of dementia. He highlighted the need for early intervention to better lower dementia risk. This is doubly important because the overall misclassification rate for hearing loss rises sharply after age 70.
Smith amplified these messages by emphasizing the need to remove any stigma about discussing hearing issues with healthcare providers. He further explained that “there are documented benefits to improved social interactions, increased quality of life from treating hearing loss.”
“So I would still encourage older adults to raise concerns about their hearing with their healthcare provider — early detection and management of hearing loss could have large benefits to their wellbeing.” – Jason R. Smith
The work doesn’t stop for Smith and his team. Their goal is to understand how the combined impact of sensory impairments on dementia occurs at the population level. They aim to identify effective strategies to reduce risk of dementia, as well as enhance sensory health among older adults.
“It’s important to consider our sensory health collectively. For example, hearing impairment and vision impairment frequently occur together in older adults,” – Jason R. Smith
Leave a Reply