Noisy Environments Impacting Hearing May Increase Dementia Risk, Study Finds

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Hearing, a skill often overlooked, is crucial for our well-being. Recent research from the past year indicates the importance of paying attention to shifts in hearing among adults, as difficulties in hearing may be associated with an increased risk of developing dementia in later life.

Examining more than 80,000 individuals aged 60 and above, the research discovered that seniors experiencing difficulty hearing speech amid noisy surroundings faced an elevated risk of dementia. Dementia encompasses various conditions marked by memory loss, language challenges, and difficulties in other cognitive functions.

On a positive note, the research contributes to the growing body of evidence indicating that hearing issues might not merely signal dementia symptoms but could serve as a potential risk factor. This suggests that such difficulties in hearing could act as an early warning for individuals, their families, or healthcare providers to anticipate the onset of dementia before any noticeable decline begins.

“There has been a specific focus on the connection between hearing impairment and the potential increase in dementia risk,” remarked epidemiologist and study author Thomas Littlejohns from the University of Oxford in July 2021. You can watch the interview here.

Although in the early stages, these findings suggest that difficulties in hearing speech amid noise could present a promising target for preventing dementia.

In 2017, hearing loss gained recognition alongside smoking and physical inactivity as one of the nine major, modifiable risk factors for dementia. This groundbreaking Lancet report underwent an update in 2020, incorporating three additional risk factors, bringing the total to 12.

The crucial term here is “modifiable.” These risk factors represent aspects of our lifestyle and overall health that are amenable to improvement. By doing so, we have the potential to enhance our overall well-being and decrease the likelihood of developing health conditions.

According to the Lancet reports, it has been estimated that among the 12 dementia risk factors, hearing loss could carry the most significant burden. This means that individuals with unaddressed hearing loss in midlife may face up to a fivefold increase in the likelihood of developing dementia.

For a deeper exploration, the researchers from the University of Oxford, conducting this study, utilized the UK Biobank. This research database is designed to unravel connections between genetics, environmental factors, and health outcomes across a substantial portion of the UK population.

The study delved into the risk of dementia among a cohort exceeding 82,000 women and men aged 60 years or older. This group, initially dementia-free, underwent an assessment of their hearing at the commencement of the study.

Participants underwent testing for their speech-in-noise hearing, assessing their capacity to discern speech snippets in a noisy setting. In this scenario, the test involved recognizing spoken numbers amidst white background noise.

Approximately 11 years later, health records indicated that 1,285 participants had experienced the onset of dementia.

Littlejohns stated that “Participants who had worse hearing had almost double the risk of developing dementia compared to those who had good hearing”.

Fascinatingly, around half of the individuals in the study who demonstrated inadequate speech-in-noise hearing, and approximately 42 percent of those with poor test performance, did not perceive any hearing impairment when queried about it.

The researchers also explored the connection between individuals’ hearing impairments and other factors acknowledged to impact dementia risk, including social isolation and depression. Both of these factors could potentially arise when individuals face difficulties in hearing.

“But we found little evidence that this was the case,” said Littlejohns.

To ensure accuracy, Littlejohns, and his team conducted additional data comparisons to assess whether individuals’ hearing performance might have been influenced by underlying, undetected dementia—a phenomenon known as reverse causation.

However, the dementia risk associated with hearing difficulties showed no significant difference when comparing study participants who developed dementia sooner (after 3 years) versus later (after 9 years); it remained relatively consistent.

While not the inaugural study to identify a connection between hearing loss and dementia, the team noted that it was among the early ones to explore the link between dementia risk and individuals’ hearing capacity in noisy environments, a scenario more representative of our daily lives.

Similarly, extensive and sizable studies from Australia and Taiwan have also observed an elevated dementia risk among individuals with hearing difficulties. However, these studies relied on either self-reported data from participants or medical records documenting hearing loss.

“Large studies like the UK Biobank are powerful tools for identifying genetic, health, and lifestyle factors linked to conditions like dementia,” commented neuroscientist Katy Stubbs from Alzheimer’s Research UK, a research charity, regarding the University of Oxford study. “However, it is always challenging to distinguish cause and effect in this type of research,” she added.

It’s crucial to remember that the most advanced epidemiological studies can only identify associations between environmental factors, health, and disease at a population level.

“It’s important to bear in mind with this type of study design you can’t infer causality,” said Littlejohns, “but this adds to the existing literature that hearing impairment could be a modifiable target to reduce the risk of developing dementia.”

It’s worth noting as well that this study proposes that safeguarding our ears from hearing damage using earmuffs and earplugs, along with enhancing hearing through the use of hearing aids, may have the potential to alleviate this identified risk factor for dementia. Given the widespread impact of dementia affecting millions globally, such preventive measures could be crucial.

In this specific study, the usage of hearing aids was limited among participants, preventing the formulation of definitive conclusions. Clinical trials are essential before further statements can be made. Nevertheless, this emerging field of investigation holds promise in advancing our comprehension and potential prevention of dementia.

The research findings were featured in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.