Untreated hearing loss could have negative effects on cognitive health. The lack of effective treatment for dementia highlights the importance of identifying modifiable risk factors to aid in the prevention of dementia.

A new large observational study shows that hearing loss is associated with an increased risk of dementia and that the use of hearing aids may mitigate this risk.
Hearing aid adoption is low among people with hearing loss. These findings highlight the need for policies to improve hearing loss diagnosis and hearing aid adoption and accessibility. Although symptoms of dementia often appear later in life, the underlying changes in the brain tend to begin in middle age. Similarly, the prevalence of hearing loss begins to increase after age 40. This has led scientists to believe that hearing loss may increase the risk of dementia, with some evidence supporting this association.

A recent large study published in The Lancet Public Health now shows that untreated hearing loss is associated with an increased risk of all-cause dementia and specific types of dementia.
In particular, people with hearing loss who used hearing aids had a similar risk of dementia as people without hearing loss, suggesting that correcting hearing loss may reduce dementia risk.

Hearing aid adoption rates are generally low among people with hearing loss, and these results highlight the importance of public health policies in increasing hearing aid adoption. These policies could include raising awareness of the potential adverse effects of untreated hearing loss, emphasizing hearing loss screening, and improving access to hearing aids by making them more affordable.

“This study adds to a growing body of research linking hearing loss to an increased risk of dementia and other health problems in older adults. It is important to raise awareness of these findings and that managing hearing loss can mitigate this risk. Hearing loss could be a cost-effective approach to reducing the burden of dementia.

Hearing loss and dementia

The lack of treatments to cure or arrest the development of dementia highlights the need to identify modifiable risk factors in order to prevent the onset of this neurodegenerative condition. Like dementia, the prevalence of hearing loss tends to increase gradually with age. Additionally, some studies have shown an association between hearing loss and an increased risk of dementia. Thus, the use of hearing aids to relieve hearing loss could potentially reduce the risk of dementia.

Indeed, there is some evidence to suggest that the use of hearing aids may delay cognitive decline and reduce the risk of dementia. In contrast, other studies have shown that there is no link between the use of hearing aids and the risk of dementia. One of the reasons for these conflicting results is the small sample size used in previous studies. Also, the association between hearing aid use and specific types of dementia has not been well studied. In the current study, researchers used a large sample to examine the association between hearing aid use and dementia risk. They also assessed the impact of hearing aid use on the risk of certain types of dementia.

Use of hearing aids and risk of dementia

The study looked at data from 437,704 people collected by the UK Biobank, a large biomedical database that collects information about participants’ genetics, health and environment. Participants had no symptoms of dementia at the start of the study and had an average age of 56 at baseline. The researchers obtained data on hearing loss through self-reports at the start of the study, while information on the diagnosis of dementia was obtained from medical records and death records. They also collected data on other variables, such as education level, income level, medical conditions, social isolation, etc., that may influence the risk of dementia or hearing loss on a mean follow-up period of 12.1 years.

The researchers found that hearing loss was more common in men than in women and in people with cardiovascular disease, obesity, depressed mood and loneliness. People with hearing loss were 42% more likely to develop dementia from any cause during the follow-up period than people with unimpaired hearing. People with hearing loss who used hearing aids did not have a higher risk of dementia from all causes than people without hearing loss. Similarly, people with untreated hearing loss, but not those using hearing aids, had an increased risk of Alzheimer’s disease, vascular dementia, and non-vascular dementia other than Alzheimer’s disease.

Failure to treat hearing loss may increase risk

These results could suggest that untreated hearing loss could increase the risk of dementia. Given the observational design of the study, the association between hearing loss and dementia could also be explained by the fact that factors associated with dementia increase the risk of hearing loss. Therefore, the researchers reanalyzed the data by excluding cases of dementia that appeared before 5 or 10 years after the start of the study. Untreated hearing loss was still associated with dementia in these follow-up analyses, suggesting that hearing loss was more likely a risk factor for dementia. Several mechanisms could potentially contribute to the increased risk of dementia due to hearing loss. For example, hearing loss may require a compensatory allocation of brain resources involved in other cognitive processes. Moreover, the absence of auditory information due to hearing loss can lead to the degeneration of brain regions involved in the processing of auditory information and, therefore, cognitive functions.

Hearing loss can also impede communication and lead to loneliness and depression. These mental health factors are also associated with an increased risk of dementia. In the current study, analysis suggests that only 11% of the reduction in dementia risk due to hearing aid use can be attributed to improved psychosocial factors, such as loneliness, social isolation and the Depression. This suggests that hearing loss may directly increase dementia risk by affecting brain regions involved in cognition.

Strengths and limitations

The analysis, which assessed the risks of different forms of dementia, indicates that treating hearing loss can reduce the risk of dementia (by) mitigating the impact of hearing loss on the brain. This could reduce the brain’s vulnerability to pathological processes related to these dementias. Further research is needed to better understand the mechanism by which hearing loss is linked to dementia.

The strengths of the study are the use of a large sample, the long duration of follow-up, and the determination of dementia based on medical reports rather than self-reports.

The authors acknowledge that the study has some limitations. These include the use of self-reported data on hearing loss, which may be inaccurate. In addition, data on hearing aid use was only collected at the start of the study. Therefore, the analysis could not take into account people who started using hearing aids after the start of the study.
The analysis also did not take into account the duration of hearing aid use, which could have influenced the risk of dementia.

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