Hearing loss is the third most common health condition affecting older adults, occurring in one-third of people over age 65 and in two-thirds of those over age 70 . It has been identified as one of the top potentially modifiable risk factors for dementia by the Lancet Commission on Dementia Prevention, Intervention, and Care . Although studies suggest that restoring auditory input may help protect cognitive function and improve quality of life , hearing aids are expensive. There are several factors to consider when determining how to cope with hearing loss.
Mild hearing loss is associated with two-fold greater risk for dementia, while severe hearing loss is associated with 5 times greater risk over 10 years . Several longitudinal studies have found that the rate of cognitive decline is accelerated in dementia patients with hearing loss . Participants with hearing loss experienced rates of cognitive decline that were 30-50% faster than those with normal hearing .
A recent study following over 1,000 participants in the Rancho Bernardo Study of Healthy Aging for up to 24 years found that hearing impairment was associated with faster age-related declines in global and executive cognitive function . The cognitive decline associated with mild hearing loss was reduced in individuals who attained higher education, but education could not protect against declines associated with moderate to severe hearing loss.
Hearing loss may promote cognitive decline because when there is less auditory input, auditory centers in the brain begin to degenerate, and the brain struggles to compensate . This means that the brain needs to use more resources to process auditory information, so that there is less available to use for other functions, such as learning and memory. Education may be protective against these early changes because it can improve resiliency, or the capacity of the brain to function normally despite the increased demands.
A brain imaging study found that areas of the brain not normally involved in language processing become activated in response to speech in people with hearing loss . This effect was seen even in healthy young adults with mild hearing loss, suggesting that brain changes which may increase dementia risk start soon after the onset of hearing damage. A separate imaging study where brain changes were tracked in 126 people for up to 10 years found that those with hearing impairment had accelerated rates of brain atrophy, including in areas involved in memory . These studies suggest that it may be necessary to treat hearing loss before significant brain shrinkage occurs in order to mitigate dementia risk.
However, it has also not been established whether correcting hearing loss can significantly reverse or slow ongoing cognitive decline. It has not been confirmed that hearing loss is driving dementia risk, since it is also possible that people prone to dementia are at higher risk for hearing loss. The ACHIEVE clinical trial (NCT03243422) is currently recruiting 850 patients for a study to test whether hearing aid use can prevent or slow dementia onset . The trial is expected to conclude in 2022.
Health insurance is not required to cover adult hearing exams . Medicare (Part B) will only cover a hearing exam if a doctor says that it is medically necessary . Hearing aids can cost thousands of dollars, but insurance is only required to cover them in 4 states (New Hampshire, Connecticut, Rhode Island, and Arkansas) . Traditional Medicare does not cover hearing aid related expenses, although some Medicare Advantage (Part C) plans do cover them . However, hearing aids may be a cost-effective investment, as healthcare costs for individuals with untreated hearing loss were found to be 46% higher over 10 years .
Hearing aids can only be obtained through a medical provider, and over the counter (OTC) hearing aids are not yet available . The products currently found in stores are hearing amplifiers, which are not FDA-regulated medical devices. Unlike hearing aids, these devices amplify all sounds, including background noise, and if they do not have automatic volume controls, they could potentially cause further hearing damage. The FDA is currently working on guidelines to establish the requirements for OTC hearing aids by 2020 . In October 2018, the FDA approved the marketing of the Bose Hearing Aid, which can be adjusted by the user through a mobile phone application . However, until the guidelines are released, these hearing aids still need to be purchased through an authorized medical provider. The availability of OTC hearing aids is expected to dramatically decrease costs.
If you or someone you know is showing signs of hearing loss such as blasting the television volume or is having trouble following conversations, it may be time to get your hearing examined. Before making an appointment be sure to check with your insurance provider to avoid unexpected medical bills.
Betsy Mills, PhD, is Senior Program Manager of Aging and Alzheimer’s Prevention at the Alzheimer’s Drug Discovery Foundation. She earned her doctorate in neuroscience at Johns Hopkins University School of Medicine, where she studied the role of glial cells in the optic nerve and their contribution to neurodegeneration in glaucoma; and completed a Postdoctoral fellowship at the University of Michigan, where she worked to uncover genes that could promote retina regeneration. Dr. Mills has a strong passion for community outreach, and served as program presenter with the Michigan Great Lakes Chapter of the Alzheimer's Association to promote dementia awareness.
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