June 29, 2022
Hearing loss is a major problem for older adults. Not only does it make it difficult to communicate with others, but it can also lead to cognitive decline. A new study has found that hearing loss is linked to an increased risk of dementia and Alzheimer’s disease.
The study, which was published in the journal Neurology, looked at data from over 1,500 adults aged 70-79. The participants were followed for 12 years, during which time they underwent tests for hearing and cognition. The results showed that those with hearing loss were more likely to develop dementia than those with normal hearing.
Additionally, recent research shows a further correlation between hearing loss and cognitive impairment. Not only can auditory sensory impairment (ARHL) lead to cognitive decline, but it may also contribute to other conditions such as depression, falls, and frailty. Additionally, ARHL can exacerbate the effects of dementia and increase the likelihood of psychotic symptoms. This suggests that ARHL should be considered a risk factor for a variety of cognitive impairments, not just one. As research into this area continues, it is becoming increasingly clear that ARHL is a complex issue with far-reaching consequences.
How hearing loss and cognitive decline are related
As studies have indicated that people with an auditory impairment are at greater risk for developing Alzheimer’s and dementia, researchers have several theories for how hearing loss can be associated with increased cognitive deterioration.
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Cognitive load: This theory suggests that as hearing loss progresses, the brain becomes overburdened under the constant pressure of comprehending sound and dialogue.
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Brain structure: This theory proposes that the physical composition of the brain is altered as brain cells atrophy from the absence of stimuli. This includes regions of the brain that both process and receive sound.
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Social isolation: Hearing loss impedes successful communication, leading to embarrassing or awkward situations. This often causes the afflicted to avoid social interaction altogether. The resulting isolation from society deprives the brain of much-needed stimulation.
The theories in detail
Increased cognitive load
Developed in 1998 by psychologist John Sweller, the cognitive load theory states that cognitive load is comprised of the amount of information processing by the brain required to perform any given task. Hence, learning becomes compromised because cognitive capacity in working memory is limited when tasks require excessive effort.
In other words, reduced or distorted sensory input will require the brain to work harder. An excessive cognitive load dedicated to auditory perceptual processing could cause relevant structural changes in the brain and neurodegeneration to the detriment of other cognitive processes, such as working memory. This often leads to a vicious cycle in which the cognitive resources available for auditory perception may be reduced, leading to cognitive decline. However, scientific evidence for this hypothesis is presently scarce.
Transformation of brain function and structure
In recent years, there has been growing evidence that hearing impairment is associated with structural transitions in brain composition. In particular, magnetic resonance imaging studies have shown that hearing loss is associated with a decreased mass of the brain and the primary auditory cerebral cortex. Hearing loss has also been linked to lower activity levels in the central auditory pathways. This can lead to a dysfunction of the auditory–limbic pathway, which is essential for processing emotions. Additionally, chronic hearing impairment has also been shown to lead to atrophy of the frontal lobe and hippocampus – both critical areas of the brain that are responsible for memory and learning.
Other changes in the brain include increased stimuli from different sensory organs, such as the eyes. As the brain makes a “compensatory” shift to processing visual information as opposed to compromised auditory stimuli, it undergoes changes known as neuroplasticity mechanisms. These mechanisms, however, are significantly destructive to cognition. In people with hearing loss, their ability to process dialogue and sounds is especially reduced by these compensatory effects. Additionally, the areas of the brain that are responsible for higher-level cognition also work harder to process sound while fulfilling their primary roles with much lower efficiency.
Social disengagement
Being socially isolated is another variable that is associated with hearing impairment and cerebral transformations. As they progressively avoid interaction for fear of embarrassing or awkward situations, people become increasingly lonely, which is a significant risk factor for cognitive diseases. Social isolation also increases the risk factor for developing apathy and depression, while reduced cognitive stimulation further impacts the brain’s compensatory changes.
Social isolation is not only emotionally damaging, but it can also have serious consequences for physical health. Studies have shown that social isolation can increase the body’s inflammatory response, which is a major risk factor for conditions such as heart disease and stroke. Isolation can also promote the transcription of pro-inflammatory genes, which can lead to further damage to brain functionality. In addition, social isolation has been linked to an increased risk of dementia and other cognitive diseases.
These studies make it clear that social isolation is a serious health hazard that should not be ignored. When people are isolated, they are more susceptible to both physical and mental health problems. Therefore, it is important to make sure that people seek treatment for their hearing loss while maintaining strong social support networks to prevent a decline in their overall quality of life. If you have further questions or concerns, do not hesitate to contact us today!