Introduction
In the intricate tapestry of human interaction, effective communication stands out as a thread that binds us to the world, connecting us with others and shaping our understanding of the environment. However, hearing disorders when aging can significantly impact our ability to interact and engage with others. Studies have shown that our sensory abilities, particularly hearing, are linked to our cognitive function.
In this blog, we'll explore the relationship between cognitive disorder and hearing impairment and how managing communication disorders is essential for overall well-being.
Definition of Hearing Loss and Cognitive Deficit in Seniors
Sensorineural hearing loss (SNHL) in the elderly is generally defined as age-related SNHL. Different mechanisms cause the auditory deterioration and, depending on the portion of the auditory pathways affected, can appear in different forms. SNHL can be classified as peripheral in case of damage limited to the cochlea or to the cochlear nerve; differently, central SNHL is referred to the damage at the level of the superior auditory pathways cochlear nuclei and auditory cortex.
Central SNHL is caused by the alteration of the superior auditory pathways (cochlear nuclei, auditory cortex) cannot be reversed. These structures can be affected by vascular damage that alters the signal transmission. Meanwhile, brain atrophy, which could be a consequence of vascular damage or aging is another potential cause of central SNHL as one of the links between cognitive decline, mild cognitive impairment, Alzheimer’s Disease and hearing loss. In fact, all conditions cause atrophy of the brain.
Cognitive decline is defined as the reduced cognitive function consequent to age, when the cognitive decline is more severe than expected for the person’s age mild cognitive impairment is diagnosed. Finally, Alzheimer’s Disease is a progressive neurodegenerative disease marked by deficits in episodic memory, working memory, and executive function. Mild cognitive impairment seems to be an early sign of Alzheimer’s Disease. In these conditions, memory (both working and short) progressively declines. In addition, psychological diseases can further impact memory function, and the elderly are more exposed to this problem.
Intimate Relationship of Hearing and Cognition
Hearing is not just about perceiving sound but it's a gateway to language acquisition, social interaction, and environmental awareness. Our auditory system, beyond just capturing sound waves, plays a pivotal role in shaping our cognitive landscape—influencing memory formation, attention span, language comprehension, and decision-making abilities and in how we process and retain information, which directly affects our cognitive abilities. Cognitive disorders, such as dementia, can affect how we process auditory information, leading to hearing impairments. Conversely, hearing loss can isolate individuals, reducing stimuli and social interactions vital for cognitive stimulation. This isolation and lack of stimulation can contribute to cognitive decline.
Therefore, when hearing is impaired, it can lead to cognitive disorders or accelerate existing ones. The cognitive disorders often coexist with hearing impairments, so conditions like dementia and Alzheimer's disease, which affect cognitive function, can be exacerbated by hearing loss, which underscores the importance of maintaining hearing health as a critical aspect of cognitive well-being.
Evaluation of Hearing Disorder with Cognitive Impairment
According to the National Institute on Deafness and Other Communication Disorders, patients with hearing loss averagely wait 7 years before seeking treatment. During this time, hearing loss may affect cognitive function leading to an irreversible decline; furthermore, hearing loss is often not detected and/or not treated in people with a diagnosed cognitive impairment.
Conversely, performances on the cognitive tests that are used in the assessment of possible dementia are affected by various factors, including sensory impairment. If a person is not able to hear the question that is being asked, he is obviously less likely to supply a correct answer. This becomes a problem when assessments are performed in environments with background noise, such as hospitals. Thus, it would be possible to misdiagnose a person with normal cognition as having cognitive impairment.
The guidelines on hearing loss recommend performing hearing test for each patient with a clinical suspicion of cognitive impairment and should be repeated every two years in subjects with a diagnosis of dementia. Patients with central hearing loss may perform normally on conventional hearing tests such as pure tone audiometry; however, they show an impaired speech perception. This condition can be associated with hidden hearing loss, in which patients show a clinically normal audiogram but a worse perception of noise probably due to damage of the inner hair cells and spiral ganglion neurons.
Tips to Manage Cognitive Disorders
Growing evidence confirms that the treatment of hearing loss through hearing solutions is an effective solution to delay the onset of cognitive impairment and maintain a good cerebral function. Treating hearing loss in people with cognitive impairment may help improving communication, increasing quality of life, and reducing behavioral symptoms of dementia, with reduced stress for families and caregivers. To date, the treatment of hearing loss in patients with cognitive decline is based on three possible options: hearing aids, amplification devices and cochlear implants.
A remarkable tool in managing hearing loss and its subsequent effects on cognition is the use of hearing aids. These devices not only amplify sound but also improve the clarity of auditory input, thereby enhancing comprehension and memory recall. Studies indicate that hearing aids can slow cognitive decline by improving access to environmental sounds and language cues, vital for maintaining cognitive function. By facilitating better communication, hearing aids can significantly enhance quality of life, social engagement, and overall cognitive performance.
Other interventions, such as hearing amplification devices and focused communication strategies, have been applied in both in-patient and outpatient settings with some evidence of benefit on outcomes such as communication and depression. We can find higher scores in cognitive tests and improved perception of communication of older hearing-impaired patients after the use of a voice amplifying device, extending to depression, neuropsychiatric and behavioral symptoms.
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Cochlear Implant
Different from conventional hearing aids, cochlear implants can restore hearing in patients with profound hearing loss. Studies available to date suggest an improvement in attention, episodic and working memory, and processing speed in cochlear implants users, even after as little as 6 months from implantation. Despite promising results, studies on cochlear implants and cognition still have some important limitations. For example, inappropriate use of measures that are delivered through hearing may overestimate cognitive dysfunction in subjects with severe hearing loss.
Conclusion
The connection between hearing and cognition underscores the importance of addressing hearing disorders holistically. By understanding this and implementing practical strategies, such as the use of hearing aids, individuals can significantly improve their hearing abilities and support cognitive health. In doing so, they can untangle the threads of communication, weaving a richer, more engaged life experience.
