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Hearing Loss and Dementia: How Are They Linked?

The older you get, the more susceptible you become to conditions like hearing loss and dementia. They are both highly common disabilities in the UK; 12 million people are living with a hearing loss, while 850,000 are battling dementia. This is equivalent to one in six for hearing loss, and one in fourteen for dementia. What many people don’t know, however, is that these conditions can occur together. Certain studies on Alzheimers and hearing loss have shown that the risk of dementia increases by 36% in people over 60, and who have a hearing loss greater than 25dB. Though experts are not exactly certain how hearing loss and dementia are connected, there are many intriguing theories, and it all seems to stem from the link between age-related hearing loss (presbycusis) and cognitive decline.

Dementia is an umbrella term for a range of cognitive symptoms that include memory loss, difficulty communication, an inability to focus, a lack of comprehension and impaired judgement. There are different types of dementia with Alzheimer’s disease being the most common. It is estimated that around 33% of people over 85 exhibit symptoms of dementia, whereas more than 70% of people over 70 experience problems with hearing loss.

Several studies from RNID have demonstrated that people with mild hearing loss are twice as likely to develop dementia. The risk increases three-fold for those with moderate hearing loss, and five-fold for a severe hearing impairment. Other studies from have shown that older adults with hearing loss – especially men – are 69% more likely to develop dementia and Alzheimer’s disease compared to those with normal hearing. Though a scientifically proven explanation has not yet been established, epidemiological and clinical studies confirm the assumption of a relationship between hearing loss and dementia. At present, there are three main theories that hypothesise this connection.

Theory One: Brain Shrinkage

Our brains shrink as we age – that is a fact, but MRIs of people with hearing loss show that the brain shrinks faster than normal. When the auditory cortex (part of the temporal lobe) grows inactive, tissues and structures in the brain begin to deteriorate. This is a result of auditory deprivation, which occurs when the brain is deprived of sound over time (such as with untreated hearing loss). The brain starts to lose its ability to process sound, leading to brain shrinkage and atrophy.

Theory Two: Cognitive Load

This is what scientists refer to as the “cognitive load theory”. As hearing becomes more difficult, the brain becomes overloaded as it struggles to comprehend what is being listened to. It then starts to work overtime to hear exactly what is being said. Straining to hear all day, every day depletes mental energy and takes brain power needed for other vital functions like decision-making and memory retention.

Theory Three: Social Isolation

Undiagnosed hearing loss opens the door to a range of unpleasant mental conditions like depression, anxiety, and paranoia. This can encourage people with untreated hearing loss to withdraw from social situations, exacerbating feelings of loneliness. As they withdraw from life, their risk of dementia intensifies. The less we stimulate our brains by interacting with other people: the less we use our brains to hear and listen, the quicker our brains decline.

Preventing Dementia: Hearing Aids

Various studies have shown that hearing aids do wonders for reducing the risk of cognitive decline and preventing dementia, alongside preserving independence, mental abilities, emotional and physical health, and social lives. One study has even proven that hearing aids slow rates of cognitive decline and improve the quality of life of those with dementia.

If someone is showing signs of dementia, it is important for them to get their hearing checked. This is because symptoms of hearing loss are often confused with those of dementia. For people who already have dementia or Alzheimer’s disease, hearing loss can aggravate symptoms. Hearing aids are no longer the “beige bananas” they used to be. They are now smaller, more discreet, and easier to use. There are also many styles suitable for those with a cognitive impairment. By reducing the risk of dementia, and alleviating symptoms, hearing aids are certainly worth it.