Why Hearing Loss Is Not Innocuous

Professor McAlpine, from the University College London Ear Institute, describes the experience of losing your hearing as being similar to visiting a foreign country where you speak only a little of the language.

You struggle to understand the conversations around you, and just trying to get by leaves you exhausted. This is exactly what happens to people who suffer hearing loss. As a result, they may start to withdraw from many of the activities they used to enjoy, because certain scenarios might tire them out, or might be embarrassing or difficult.

Recent studies by Dr Frank Lin and his team at Johns Hopkins University in Baltimore, suggest that this could have a worrying knock-on effect as evidence is beginning to emerge that hearing loss contributes to accelerated declines in the cognitive and physical functioning of older adults.

Much of Dr Lin’s research over the last few years has focused on investigating whether hearing loss is independently associated with cognition and dementia. He has collaborated with other aging researchers and has analyzed observational epidemiologic data from the Baltimore Longitudinal Study of Aging, the Health, Aging, and Body Composition Study (HealthABC), and the National Health and Nutritional Examination Surveys (NHANES). Through these studies, he has shown that hearing loss is independently associated with poorer cognitive functioning on non-verbal tests of memory and executive function, accelerated cognitive decline, the risk of developing dementia, and accelerated rates of brain atrophy.

Hearing loss and dementia are definitely linked. The nature of the connection between the two needs to be studied further. Three possible links are suggested by Dr. Lin.

1. Social isolation.
Studies show that being sociable and taking part in activities protects against dementia, possibly because it relieves stress, which is known to be harmful to the brain. So taking yourself out of daily interactions (because your hearing problems make them impossible) may increase the risk of memory loss and cognitive problems.

2. Brain overload.
As hearing loss occurs, more of the brain’s resources are dedicated to hearing and understanding, at the expense of other brain functions. According to Dr Lin, “If you’re constantly expending more resources to help with hearing that probably comes at the expense of systems such as thinking and memory and cognition.”

3. Underlying cause.
It may be that hearing loss and dementia share a common cause. What this common cause might be is still unclear and needs further study. Perhaps as we learn more, the connection will become clear.

While many patients regard hearing loss as a natural and harmless consequence of aging, Dr Lin’s research suggests that compared with normal hearing, people with hearing loss are more likely to have dementia. The Baltimore Longitudinal study of Aging found that the more severe the hearing loss, the greater the risk of dementia.

Whatever the link between hearing loss and dementia, untreated hearing loss can have serious consequences.

References:
Dementia and hearing loss: methinks hearing aids are not enough, Sandra Vandenhoff
How your hearing aid could stop you getting dementia, Professor David Mcalpine

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