According to the World Health Organization, 35.6 million Americans have been diagnosed with dementia and 38 million Americans have been diagnosed with hearing loss. The consequences of hearing loss stretch beyond the ears. Several health effects including a more rapid rate of cognitive decline are statistically significant in those with hearing loss compared to those without (Lin et al., 2013). You can find the full study on dementia and hearing loss here.
Individuals with hearing loss partake in effortful listening. They often have to watch those who are speaking and are easily distracted by background noise. They find they are using maximum effort just to hear. Effortful listening can lead to memory decline and social isolation. Memory decline and social isolation are known risk factors for developing dementia. The slippery slope towards dementia, originating from hearing loss, deserves attention.
Previous studies support that those with hearing loss are more likely to be diagnosed with dementia. More recent studies have statistical power and account for variables to address that this conclusion may be an independent correlation between hearing loss and dementia and not just a factor of age.
A Johns Hopkins study completed in 2013 suggests that the risk of dementia increased linearly with the severity of hearing loss. Those with just a mild loss were twice as likely to develop dementia as those with normal hearing, while moderate were three times as likely, and severe was five times as likely. This study concludes that hearing loss is independently associated with dementia. Future studies are encouraged to determine if hearing loss is an adjustable risk factor or an early marker for dementia.
Further Johns Hopkins studies found that cognitive-decline occurred 3 years faster in those with a slight hearing loss than their normal-hearing age-matched peers. It further goes on to suggest that hearing loss is independently associated with cognitive decline. The severity of baseline test results was linearly correlated with an increased risk of cognitive impairment, meaning, those with mild hearing loss are twice as likely to develop dementia compared to those with normal hearing. The risk increases three-fold for those with moderate hearing loss, and five-fold for those with severe impairment. These results suggest hearing loss may be a possible modifiable risk factor for dementia.
Hearing loss side-effects go beyond the ears. Social isolation is a symptom of both hearing loss and dementia. Difficulties in hearing result in withdrawal from social environments. Several studies suggest those in rich social networks display more neural growth and fewer cortisol levels, resulting in healthier maintenance of cognitive function. Hearing loss causes social isolation, effortful listening, and/ or reduced sensory nerve stimulation; all of which are the result of the apparent correlation between hearing loss and dementia.
The theories expressed all shed light on the importance of further exploration of the underlying cause for the correlation between hearing loss and dementia. If the theory of cognitive reserve, social isolation, and/or neuronal stimulation proves to be true, one can see the importance of early treatment of hearing loss. Hearing aids may free-up cognitive reserve, increase social interaction, and/or provide nerve stimulation in an attempt to reduce the risk or severity of dementia. Hearing health is so much more than just your ears.