The role of hearing aids in the fight against dementia

Each year, there are several million new cases of dementia. Alzheimer disease is the most common form of dementia. It is estimated that presently approximately 50 million people have dementia.   The World Health Organization, WHO, is forecasting a threefold increase by 2050. The consequences for those affected and their families are immense.

The illness is still incurable. However, research regularly presents new findings on dementia that lead to new treatment approaches and produce important information on preventive measures.

A broad-based study in Taiwan recently investigated the connection between hearing loss and dementia. The conclusions of the researchers together with the role that hearing aids could play in the battle against dementia is the focus of this blog post. 

Dementia basics

Dementia is a long-lasting disease that affects and incapacitates people in many ways.  It negatively impacts cognitive abilities such as thinking, memory, spatial orientation, language, general understanding and the ability to undertake everyday tasks. Over the course of time these skills diminish more and more. 

People with Alzheimer’s frequently withdraw from society and lose the zest for life. The mental, physical, social and economic consequences are immense, not just for the victims themselves, but also their relatives, carers and families. This is primarily due to common misconceptions and a lack of awareness of the disease, and the cost of care and treatment. Dementia is one of the major causes of disability and dependency among the elderly. 

The World Health Organization has estimated that 50 million people are currently affected by dementia and the number of cases rises by approximately 10 million annually. Dementia is the fifth most common cause of death in industrialized countries.

Dementia emerges in a variety of forms. The most well-known and most widespread form is Alzheimer disease. Sufferers experince a build-up of protein deposits in the brain.  In time, nerves wither and the connection between cells is lost. About two thirds of people with dementia have Alzheimer's.

Vascular dementia is also relatively well known in the general population. This is caused by a reduced blood flow to the brain and can affect different areas of the brain. Vascular dementia accounts for about one fifth of all cases.

As a rule, dementia is a disease of the elderly. About two thirds of all dementia cases are people of 80 years of age or older. The risk of developing dementia increases with age. If you consider people aged 90 and over, about 40% have dementia. In general, more women than men are affected by dementia, and this correlates to the higher life expectancy of women.

Symptoms

The symptoms of dementia fall into three different stages.

Initially, general forgetfulness becomes a problem. Victims of dementia lose their sense of time and the ability to maintain an overview. They become confused and disorientated even in familiar places. The illness often goes undiagnosed in this phase because the sufferer and the people around them do not discern the severity of the symptoms.

As the illness advances, the negative effects intensify as do the limitations the sufferers experience. Short term memory declines rapidly and even recent events are forgotten. This becomes apparent, for example, when the victim repeats the same question at short intervals. Equally, memory for names functions less well, and contact and interaction with other people reduces and reduces.  Even within their own four walls, the victims lose their orientation and begin to wander around confused and lost.  Significant changes in behavior are usually observed.  It is likely that the victims require physical support at this stage, for example, with personal care.

As the dementia develops, independence is lost, and impediments increase. Cognitive abilities are extremely restricted and there are serious memory problems. Sufferers are unable to recognize close relatives and friends.  The sense of time is much reduced, and individuals affected do not know where they are. Physical dependency generally also increases. Movements become slower and walking more difficult. The requirement for care also increases at this stage. Changes in behavior and potentially aggressive behavior can be very challenging and difficult. 

Treatment of dementia

There is currently no known treatment to cure dementia, or even the means to keep the illness adequately at bay.  However, research institutions the world over are working to combat dementia.

It is important to gain both an understanding of dementia and knowledge of the disease, and the correct way of dealing with it. Early diagnosis is just as helpful as the close involvement of doctors and nursing staff and ensuring they are provided with enough information. 

In addition, steps to prevent the disease can be very important. Scientific advances in diagnosis and early detection have led, at least in western countries, to a reduction in the risk of dementia.

Although, in general, older people over the age of 65 tend to develop dementia, the illness can also affect younger people and there are various factors that are significantly related to the development of dementia.  

Studies have shown that people can reduce the risk of dementia by moving adequately, not smoking, consuming alcohol moderately, not being overweight, eating healthily and taking care of their health. Feelings of loneliness, cognitive inactivity or depression are risk factors.

A recent study from Taiwan published in 2019 has again confirmed the link between hearing loss and dementia.

Hearing difficulties and loss of hearing increase the risk of dementia. This applies particularly to people of advanced middle age. In a survey of about 16,000 people, the researchers established that that for people aged from 45 and 64, the risk of developing dementia in later life is significantly higher when they have hearing problems.  In the control group of people without hearing difficulties, the illness was present at a lower level. The researchers consider deafness to be one of the most important risk factors for middle-aged people.

The link between hearing loss and dementia

In a broad-based study entitled "Association of Hearing Loss with Dementia”(2019), the researchers Chin-Mei Liu and Charles Tzu-Chi Lee investigated the link between loss of hearing and the later development of dementia in the Taiwanese population. In their cohort study, the pair used data from the National Health Insurance Research Database of Taiwan. They compared 8,135 people who had been diagnosed with hearing loss between 01 January 2000 to 31 December 2011 with a control group consisting of 8,135 people who were not affected by hearing loss.  Short-term hearing loss lasting less than 1 year was not taking into consideration or not evaluated as such. Of the participants, 9,286 were men (57.1 percent) and 6,984 women (42.9 percent). The average age of the test subjects was 65.2 years. Distribution of the participants in the "hearing loss" and "no hearing loss" groups was almost the same. 

The authors took into consideration a range of control variables and compounding factors. In addition to demographic data such as age, gender, origin or insurance cover, other factors specifically encountered with dementia were also incorporated.  The authors listed:

“coronary artery disease (ICD-9-CM codes 410-415), cerebrovascular disease (ICD-9-CM codes 362.34 and 430-438), chronic obstructive pulmonary disease (ICD-9-CM codes 491, 492, 494, and 496), types 1 and 2 diabetes (ICD-9-CM codes 250 and 251), chronic kidney disease (ICD-9-CM codes 580-589), hypertension (ICD-9-CM codes 401-405), hyperlipidemia (ICD-9-CM code 272), anxiety (ICD-9-CM codes 300.0, 300.01, 300.02, 300.2, 300.21, 300.23, and 300.3), depression (ICD-9-CM codes 311, 296.2, 296.3, 296.82, 293.83, and 300.4), alcohol-related illness (ICD-9-CM codes 291, 303, 305.0, 571.0, 571.1, 571.2, 571.3, 790.3, A215, and V11.3), head injury (ICD-9-CM codes 800-804, 850-852, 853.1, 853.2, 854.0, 854.1, A290-291, and A470), rheumatoid arthritis (ICD-9-CM code 714), and asthma (ICD-9-CM code 493).” (Liu, Chin-Mei; Lee, Charles Tzu-Chi 2019, p. 3)

Of the 16,270 participants in the study, 1,868 developed dementia. More people developed dementia who had hearing loss (1,094, that is 58.6%). Of the participants without hearing loss, 774 developed dementia, which is equivalent to 41.4 percent. That means, of the participants who had hearing loss, 19.38 per 1,000 people developed dementia annually, and in the control group, the figure was about 13.98 per 1,000 people. The authors undertook a Kaplan Meier analysis which indicated a significant difference between the two groups.

Even after considering the control variables, a positive correlation between hearing loss and dementia was apparent. The correlation was particularly strong for the group of 45 to 64-year-olds. Although the study had limitations in certain areas, it demonstrated the significant role that hearing loss plays in dementia and produced some interesting results. 

Earlier studies could also be confirmed (compare Ford et al. 2018; Thomson et al. 2017).  Several years ago, Uhlman et al. (1989) determined a significant correlation between hearing impairment and dementia. Similarly, for Zheng et. al. (2017). In their meta-analysis, they concluded that hearing loss significantly increased the risk of developing dementia later in life. 

As a rule, all studies have certain limitations. In examining the connection between hearing loss and dementia there is always the difficulty mentioned of proving causality.  Even the precise diagnosis of dementia is a challenge for the researchers.

Overall, it is fair to say that hearing loss meanwhile is considered one of the biggest risk factors for dementia.

How hearing aids can help 

Why hearing difficulties are related to dementia, has yet to be fully explained. However, hearing loss leads to people having difficulty following conversation, particularly in environments with scattered background sounds.  Communication with fellow human beings becomes more difficult, which results in social isolation, low spirits and in the worst-case scenario depression, which in turn increases the risk of dementia.  People with impaired hearing participate less in social life and consequently have less input and motivation. They have fewer cognitive stimuli. And fundamentally, the onset of dementia is promoted by the absence of acoustic stimuli (see Dawes et al. 2015; Uhlmann et al. 1989). 

Hearing aids, and in extreme cases cochlea implants (hearing protheses for the deaf whose hearing nerve is still active) can be useful. Studies have shown that hearing aids that promote social interaction between people and have a positive effect on the cognitive abilities of the wearers (see Hughes et al. 2018; Dawes et al. 2015).

One intervention can, and should be, the earliest possible diagnosis of hearing loss and the use of hearing aids, if possible, at an early age. The shorter the time between the start of hearing loss and the use of a hearing aid, the lower the loss of mental capacity.  In addition, it is easier to get used to a hearing aid when the loss of hearing is not advanced. People with hearing loss are often loath to resort to a hearing aid, as hearing aids have not yet achieved the same acceptance in society as, for example, spectacles. People often associate hearing aids with aging. But hearing aids contribute considerably to an improved quality of life. The benefit of a hearing aid is commonly underestimated. In addition, the aids are becoming smaller and can scarcely be seen by third parties. The designs of hearing aids are also continually being updated to meet the high expectations of wearers and consumers.

The positive effect that hearing aids have as a potential means to prevent dementia should be another reason for all hearing-impaired people to take advantage of a hearing aid as soon as possible.

Info: Hepako GmbH is a supplier of precision rubber items for medical devices. This includes the hearing aid industry, which Hepako GmbH supplies with a range of components. More information can be found here.

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Sources:

Dawes, Piers/ Emsley, Richard/ Cruickshanks, Karen J./ Moore, David R./ Fortnum, Heather/ Edmondson-Jones, Mark/ McCormack, Abby/ Munro, Kevin J. (2015): Hearing loss and cognition: the role of hearing aids, social isolation and depression. PLoS One. 2015;10(3).

Ford, Andrew H./ Hankey, Graeme J./ Yeap, Bu B./ Golledge, Jonathan/ Flicker, Leon/ Almeida, Osvaldo P. (2018): Hearing loss and the risk of dementia in later life. Maturitas. 2018; 112:1-11.

Hughes, Sarah/ Hutchings Hayley/ Rapport, Frances/ McMahon Catherine/ Boisvert, Isabelle (2018): Social connectedness and perceived listening effort in adult cochlear implant users: a grounded theory to establish content validity for a new patient-reported outcome measure. Ear Hear. 2018;39(5):922-934.

Liu, Chin-Mei/ Lee, Charles Tzu-Chi (2019): Association of Hearing Loss with Dementia, JAMA Network Open. 2019;2(7).

Thomson, Rhett S./ Auduong, Priscilla/ Miller Alexander T./ Gurgel, Richard K. (2017): Hearing loss as a risk factor for dementia: a systematic review. Laryngoscope Investigative Otolaryngol. 2017;2(2):69-79.

Uhlmann Richard F./ Larson Eric B./ Rees Thomas S./ Koepsell Thomas D./ Duckert Larry G.: Relationship of Hearing Impairment to Dementia and Cognitive Dysfunction in Older Adults. JAMA. 1989;261(13):1916–1919.

Zheng, Yuqiu/ Fan, Shengnuo/ Liao, Wang/ Fang, Wenli/ Xiao, Songhua/ Liu, Jun (2017): Hearing impairment and risk of Alzheimer´s disease: a meta-analysis of prospective cohort studies. Neurological Sciences, Vol. 38, 233-239.