Dementia is something all of us want to avoid, and we are willing to take steps in our lifestyle to ward it off. But there is something that contributes to the decrease in our mental capacity, and it’s the loss of hearing.
Worldwide up to 1.5 billion people have hearing loss which may reach 2.5 billion by 2030. Fifty-five million people have dementia, and we are now learning that hearing loss, a factor not considered previously, may play a role in its development.
Research studies have now identified midlife hearing loss as an independent risk factor for dementia, which is involved in 9% of cases of dementia. The question which begs an answer is how could hearing loss be related to dementia, and this is the area where hearing pathology and the amelioration of hearing loss may play significant roles.
Healthcare professionals already saw the effect hearing loss had on the emotional state of their patients. Patients with mild to moderate hearing loss were often depressed and began to seclude themselves, avoiding conversations in groups or settings where music was playing. It decreased their interest in social activities, and, therefore, hearing loss began to affect their physical stability as well. Less interaction often leads to fewer physical activities, which plays a role in physical and emotional health as it also affects the immune system.
Researchers now know that the brain’s memory center, the hippocampus, is also affected by hearing loss. Studies have shown a direct relationship between manipulating auditory information, whether speech, music, environmental, emotional or other sounds, with this prime memory area of the brain.
Hearing involvement in cognitive processing and dementia may be worse than patients realize. In a study that tracked 639 adults for nearly 12 years, Johns Hopkins expert Frank Lin, M.D., Ph.D., and his colleagues found that mild hearing loss doubled dementia risk. Moderate loss tripled risk, and people with a severe hearing impairment were five times more likely to develop dementia.
Hearing loss, therefore, is a formidable challenge in terms of dementia and maintaining cognition. Various brain scanning methods have verified the physical extent to which brain atrophy is affected by hearing loss.
Although hearing loss may come as a function of aging and changes in the hearing mechanism of the ear, we now know that environmental noise can exacerbate this loss and bring on neuropsychiatric outcomes such as memory impairment, a.k.a. dementia. The sources identified as most concerning for noise exposure include traffic noise and other environmental noise-producing factors. This could be most relevant in job situations where noise is constantly present.
Not only does noise affect hearing, but it also affects the central nervous system and the brain, which may increase the risk of stroke, dementia, cognitive decline, neurodevelopmental disorders, depression, and anxiety disorder.
The Role of Hearing Aids
The question of hearing loss and its relationship to dementia also brings into consideration another question; would treatment with hearing aids be helpful in either delaying dementia or in reversing some forms of it? Previously, studies that attempted to measure cognitive outcomes when hearing interventions were provided have been short-lived because of the general population’s lack of hearing aid use or compliance.
Hearing aids have been out of the financial reach of many (costing between $4-$6K) or have been unsuitable because of their design or effects on environmental sounds; we have little evidence to go on. Now, however, that the FDA has agreed to the provision of selling over-the-counter hearing aids and negating the need for a medical exam or an audiology exam, there may be noticeable changes in the hearing-loss population.
The difficulties, however, still exist because many will find the units out of reach for them because of pricing. Still, we hope that competition and technological developments and innovations will make them available to the larger population.
Could hearing aids be remediation in some manner and tap into the brain’s ability to change the hippocampal structures destroyed through hearing loss? Biologists know that the brain contains stem cells that might be brought into use through innovative techniques not yet envisioned by researchers but potentially viable in abstraction.
Could these hippocampal cells be prompted to replace sections devoted to cognition that are atrophied by hearing loss? The question is intensely exciting and necessitates research toward that end.