Hearing Aids, Cochlear Implants and Dementia

 

Background

Presbycusis is associated with accelerated cognitive decline, dementia and depression. Affected individuals suffer difficulty communicating, social isolation, loss of autonomy and general psychological involution. Memory and concentration decline 30 – 40% faster in older adults with hearing loss than in those with normal hearing (1,2). Further, the risk of developing dementia increases proportionately with the amount of hearing loss.

 

·Mild loss

2x risk of dementia

·Moderate loss

3x risk

·Severe loss

5x risk

New Information

 

Two new studies help connect the dots between presbycusis and dementia. In the first, data from an animal model of cognitive impairment suggest that hearing loss may result in age-related cognitive dysfunction. In the second, general mental health of hearing impaired older adults is shown to improve with the appropriate use of hearing aids or cochlear implants.

 

So and colleagues (3) from The Catholic University of Korea (Seoul, Korea), recently suggested a causal relationship between hearing loss and cognitive impairmentusing standard mouse models of cognitive function. The experimental group, mice with NIHL, had poorer cognitive function after 6 months than normal hearing controls. Some basic questions, such as a possible direct effect of sound-deafening on performance and correlation of the degree of HL with cognition, leave room for further investigation. Although replication is necessary, this is (to our knowledge) the first study to support a causal relationship between HL and dementia.

In another recent paper, Contrera and colleagues (4) from Frank Lin’s group at Johns Hopkins demonstrated improved generic (that is, not disease-specific) mental health quality of life in hearing impaired older adults after 12 months use of a hearing aid (for moderate HL) or CI (for severe – profound HL). CI users improved nearly twice as much as HA users, partly a reflection of lower baseline scores. The safety and utility of CI in older adults, up to 80 and 90 years of age, has been demonstrated (5).

 

Take Home

 

A somewhat nebulous relationship between HL and dementia has been widely accepted for some time. These new studies begin to support the notion that HL may be one cause of age related decline in cognitive function and that appropriate intervention with hearing aids or cochlear implants may be effective in the management of dementia.

 

References

1. Lin FR. Hearing loss and cognition among older adults in the United States. J Gerontol A Biol Sci Med Sci2011;66:1131–6.

2. Lin FR, Yaffe K, Xia J, Xue QL, Harris TB, Purchase-Helzner E. Hearing loss and cognitive decline in older adults. JAMA Intern Med 2013;173:293–9.

3. So YPMin JKHuerxidan S, Dong-Kee K,Sang WY, Shi NP. A causal relationship between hearing loss and cognitive impairment. Acta Oto-Laryngolgica. Epub ahead of print (2016). DOI: 10.3106/00016489.2015.1130857.

4. Contrera KJ, Betz J, Lingsheng L, Blake CR et al. Quality of Life After Intervention With a Cochlear Implant or Hearing Aid. Laryngoscope e Pub before print DOI: 10.1002/lary.25848 (2016).

5. Eshraghi AA, Rodriguez M, Balkany TJ. Cochlear implant surgery in patients more than seventy-nine years old. Laryngoscope (2009) 119:1180-1183.