Does Hearing Loss Cause Dementia?
07 December 2020
This is a commonly asked and important question. Unfortunately, what we are seeing in often reported in the news can be a stretch. The important term to distinguish here is the term “cause”. There is currently no evidence to show that hearing loss causes dementia. What there is evidence to support is that individuals with worse hearing tend to demonstrate poorer cognitive function.
Research also indicates a higher rate of comorbidity of hearing loss and dementia; meaning they often occur in the same individuals.¹ Dr. Frank Lin’s is a leading researcher in this topic area and has demonstrated accelerated cognitive decline by 30-40% in those who have hearing loss compared to those who have normal hearing. He has also shown increased risk of dementia in older adults with hearing loss and that the greater the degree of hearing loss, the greater the likelihood of dementia.²
Why we see this between hearing loss and reduced cognitive abilities is a topic still being heavily researched, however there are some proposed theories. For one, we know that individuals with hearing loss tend to require more effort listening compared to those who do not have hearing loss. This extra cognitive effort may lead to fewer cognitive resources available for other tasks, presenting as decreased memory or cognitive function.
Another possibility is an indirect association between hearing loss and cognition; it is well established that untreated hearing loss can lead to social isolation, depression, and reduced self-efficacy. These characteristics are also known to be linked to having an increased risk of dementia¹. Anecdotally, as a clinician, I have seen many patients brought in for their initial appointment by a family member who also expresses concern for memory loss. The individual is found to have a hearing loss, we pursue the appropriate form of management, and both the family and myself are shocked by the change in the individual with hearing loss’s personality, involvement in the conversation, demeanor, and overall functional ability simply because they have greater access to communication and their environment.
Another commonly proposed theory linking hearing loss and cognitive decline is auditory deprivation. We know that when individuals live with untreated hearing loss for extended periods of time, their auditory system is deprived of critical input. Eventually the auditory system loses its ability to process this input, even when it is loud enough to hear. Think of this like exercise and the importance for your muscles and body to keep moving and exercising. The longer you go without movement, the more your muscles atrophy and the harder it is to comeback and rebuild strength. It has been suggested that this auditory deprivation, from lack of hearing, may have an impact on cognitive abilities. Finally, the ‘common cause’ hypothesis suggests that age-related changes and degeneration lead to both hearing loss and cognitive decline.³
Ultimately, someone who has age-related hearing loss does not necessarily need to fear that they will suddenly or certainly develop dementia. Rather than saying “hearing loss causes” dementia, it is more appropriate to say is that there is an association, or possible link, between cognitive function and hearing loss. Based on the current research, it is recommended that an individual showing signs of memory loss or cognitive decline consider having a hearing evaluation and address hearing loss and communication as one step of the process.