Numerous studies have been conducted to evaluate the relationship between hearing loss and dementia in elderly patients. These studies show that older people with hearing loss are much more likely to develop dementia during their lifetime compared to people with normal hearing.
Does hearing loss affect dementia?
In one of the first studies published in 1989, Richard Uhlmann and his colleagues compared 100 subjects with dementia with 100 subjects without dementia (control group) who had the same age, gender, and education level. They concluded that hearing loss contributed to cognitive impairment in older adults: the greater the hearing loss, the higher the likelihood of dementia.
Detailed analysis of the data showed that the proportion of patients with dementia believed to be due to hearing loss could be as high as 32%. The study also showed that hearing loss was associated with reduced cognitive performance, even in patients who did not have dementia.
That physician should pay particular attention to the possible presence of hearing impairment when diagnosing dementia. In parallel, hearing impairment may be an important risk factor for dementia and cognitive impairment. If this is the case, correction of the hearing impairment, for example with hearing aids, would not prevent the progression of dementia, but could significantly improve the symptoms of the disease.
Thus, correction of hearing impairment would be a promising treatment for cognitive impairment in the elderly, especially since there are currently no alternative means to alter the course of common dementias, such as Alzheimer's disease.
Hearing aids significantly reduce the risk of developing dementia
People with hearing loss have a higher risk of developing dementia. This is shown by several studies: For example, British researchers investigated nine causes of dementia (Livingston et al. 2017). According to the study, hearing loss is responsible for about nine percent of the risk in middle-aged people. Hearing loss is the most significant factor that can potentially be influenced, ahead of lack of education, smoking, depression, too little exercise, and social isolation. Researchers at Johns Hopkins School of Medicine in the U.S. have also found that people with untreated hearing loss are up to five times more likely to develop dementia.
The good news is that hearing aids can mitigate this development. For example, two studies already found that the use of hearing aids increases mental abilities. This is true regardless of social isolation or depression. Therefore, the positive effect of hearing aids is directly attributable to the improvement in hearing ability. Hearing aids also counteract the risk of becoming dependent on others to manage daily life in old age.
Causal links between hearing loss and dementia still unclear
However, the exact associations of hearing loss and dementia are still unclear. One possible cause of dementia is the weaker acoustic signals caused by hearing loss. If the brain no longer receives certain auditory impressions over a longer period of time, it forgets how to process them - thus increasing the risk of dementia.
Similarly, constant stress and focus on hearing could also lead to neglect of other brain functions. In contrast, hearing-impaired people who wear hearing aids have been shown to have the same cognitive level as people with normal hearing.
Regular hearing tests to prevent hearing loss
Accordingly, experts recommend regular hearing tests. This also applies to younger people, for whom the issue of dementia seems very remote. While 99 percent of 14- to 19-year-olds still hear well, only 95 percent of 30- to 39-year-olds and 75 percent of 50- to 59-year-olds do.
About 24,000 people in Germany are already affected by dementia before their 65th birthday. Untreated hearing loss can influence an earlier onset of dementia. Seeing an ENT specialist or hearing care professional at an early stage therefore not only helps to preserve hearing ability in old age. If hearing loss is treated, those affected remain mentally fitter in old age and maintain their quality of life.
Weak ears favor forgetfulness
People who can hear well are very likely to remain mentally fit much longer in old age - this connection has been confirmed by a major new study from Taiwan. The extensive study over eleven years with health data from 16,000 participants shows that people with hearing loss have a 50 percent higher risk of developing dementia.
The risk of dementia is greatest among those with poor hearing between the ages of 45 and 64. The study found that hearing loss in slightly younger people can actually cause severe cognitive impairment due to impaired speech perception. In addition, age-related hearing loss can lead to accelerated aging. This is because to compensate for weak ears, the brain additionally activates the frontal areas during increased listening efforts.
This constant overuse causes it to age faster. This also affects the way the different areas of the brain work together - which can lead to a depletion of cognitive reserves. The good news is that the negative effects of hearing loss on forgetfulness can be counteracted.
Studies have shown that hearing aids slow down cognitive decline. It is therefore important to take action at the first suspicion of declining hearing. In fact, the results of the study suggest that hearing should always be tested in middle age as a precaution. This can now be done easily and discreetly.