A recently recognized link, whether age-related hearing loss causes dementia remains unclear. Regardless the nature of their association, since most age-related hearing loss is peripheral, not central, an age-related hearing loss-dementia link has immense practical importance given the rapidly increasing life expectancies and aging populations the world over. If simple relatively low-tech interventions such as hearing aids help prevent or mitigate aspects of cognitive decline, an economical yet tremendous medical benefit could be close to hand.
This answer* summarizes
- Conceptual models currently used to explain the link between age-related hearing loss and cognitive decline.
- Research on whether hearing aids help reverse cognitive decline associated with age-related hearing loss.
- History of research on age-related hearing loss- cognitive decline link.
- Epidemiological data supporting age-related hearing loss- cognitive decline link.
* For clarity, except where necessary, the answer uses the term cognitive decline (process), not dementia (outcome).
Conceptual Models Currently Used to Explain Age-related Hearing Loss-Cognitive Decline Link
A currently prevailing hypothesis presumes age-related hearing loss forces the person to expend an increasing amount of mental effort not only in straining to listen and understand what others around them are saying but also in trying to discern signal from noise in everyday life (social events, TV/radio/online, public announcements in airports, etc., ambient sounds and the like).
Such sustained unnatural effort is considered to set up a vicious cycle where certain parts of the brain get strained while working memory is weakened.
While there is as-yet no definitive evidence supporting either tack, the main difference between two different frameworks that link age-related hearing loss and cognitive decline is whether (see below first from) or not (see below next from 2) the two processes have a common trigger.
Could Hearing Aids Help Reverse Some Types of Cognitive Decline Associated with Age-Related Hearing Loss?
While a couple of studies have shown hearing aids deployed for age-related hearing loss improved working memory (, 4), definitive evidence for hearing restoration stemming or stopping cognitive decline is as-yet (circa 2018) lacking.
Representing a first, a randomized clinical trial, begun on January 4, 2018 and running through May 2022, is recruiting ~850 70 to 84-year old cognitively normal individuals with hearing loss to be (see below from)
‘randomized 1:1 to the hearing intervention (hearing needs assessment, fitting of hearing devices, education/counseling) or successful aging intervention (individual sessions with a health educator covering healthy aging topics). Post baseline, participants will be followed semi-annually for 3 years’
History of Research on Age-related Hearing Loss-Cognitive Decline Link
The idea that a ‘peripheral sensory defect‘ such as sight or hearing might be linked to age-related cognitive decline was apparently first proposed in 1964 (), briefly explored in the 1980s ( , 8, 9, 10) and then seemingly forgotten ( ) until a series of groundbreaking collaborative observational studies by scientists at and the (NIA) ( , , , ) between 2011 and 2013 revived interest in this idea.
Epidemiological Data Supporting Age-related Hearing Loss- Cognitive Decline Link
The gist from a recent flurry of epidemiological studies is relative risk of dementia from hearing loss is higher than for any other individual risk factor (, , 18, see below from ).
‘The risk of hearing loss for dementia in the meta-analysis of three studies,65–67 which we did for this Commission (pooled RR 1·94, 95% CI 1·38–2·73; figure 3), is not only higher than the risk from other individual risk factors, but it is also pertinent to many people because it is highly prevalent, occurring in 32% of individuals aged older than 55 years.91 Its high RR and prevalence explains the high PAF [population attributable fraction]. We have used the prevalence of hearing loss in individuals older than 55 years to calculate PAF because this age was the youngest mean age in which presence of hearing loss was shown to increase dementia risk.67 Hearing loss is therefore grouped with the midlife risk factors, but evidence suggests that it continues to increase dementia risk in later life.’
However, mutually antagonistic factors complicate accurately assessing the extent to which hearing loss and dementia are linked, with one set of factors contributing to underestimating the extent of hearing loss in the population at large, and another to overestimating the link between hearing loss and cognitive decline.
- Hearing loss underestimation: May be considerably underestimated since hearing loss tends to be under-diagnosed and under-treated ( , ). People apparently also often do not use prescribed hearing aids (22), which may exacerbate propensity for cognitive decline.
- Hearing loss-cognitive decline link overestimation: Catch-22 aspect to measuring cognition and hearing loss since tests assessing the former frequently rely on intact hearing. , the gold standard clinical assessment for hearing loss, may thus overestimate degree of cognitive impairment in those with hearing loss, especially in tests that require auditory function (2).
1. Lin, Frank R., and Marilyn Albert. “Hearing loss and dementia–who is listening?.” (2014): 671-673.
2. Wayne, Rachel V., and Ingrid S. Johnsrude. “A review of causal mechanisms underlying the link between age-related hearing loss and cognitive decline.” Ageing research reviews 23 (2015): 154-166.
3. Doherty, Karen A., and Jamie L. Desjardins. “The benefit of amplification on auditory working memory function in middle-aged and young-older hearing impaired adults.” Frontiers in psychology 6 (2015): 721.
4. Qian, Zhen Jason, et al. “Hearing aid use is associated with better mini-mental state exam performance.” The American Journal of Geriatric Psychiatry 24.9 (2016): 694-702.
6. KAY, DW, M. ROTH, and P. BEAMISH. “OLD AGE MENTAL DISORDERS IN NEWCASTLE UPON TYNE. II. A STUDY OF POSSIBLE SOCIAL AND MEDICAL CAUSES.” The British journal of psychiatry: the journal of mental science 110 (1964): 668.
7. Herbst, Katia Gilhome, and Charlotte Humphrey. “Hearing impairment and mental state in the elderly living at home.” Br Med J 281.6245 (1980): 903-905.
8. Weinstein, Barbara E. “Hearing loss and senile dementia in the institutionalized elderly.” Clinical Gerontologist 4.3 (1986): 3-15.
9. Peters, Christie A., Jane F. Potter, and Susan G. Scholer. “Hearing impairment as a predictor of cognitive decline in dementia.” Journal of the American Geriatrics Society 36.11 (1988): 981-986.
10. Uhlmann, Richard F., et al. “Relationship of hearing impairment to dementia and cognitive dysfunction in older adults.” Jama 261.13 (1989): 1916-1919.
11. Valentijn, Susanne AM, et al. “Change in sensory functioning predicts change in cognitive functioning: Results from a 6‐year follow‐up in the Maastricht Aging Study.” Journal of the American Geriatrics Society 53.3 (2005): 374-380.
12. Lin, Frank R., et al. “Hearing loss and incident dementia.” Archives of neurology 68.2 (2011): 214-220.
13. Lin, Frank R., et al. “Hearing loss and cognition in the Baltimore Longitudinal Study of Aging.” Neuropsychology 25.6 (2011): 763.
14. Lin, Frank R., et al. “Hearing loss prevalence and risk factors among older adults in the United States.” Journals of Gerontology Series A: Biomedical Sciences and Medical Sciences 66.5 (2011): 582-590.
15. Lin, Frank R., et al. “Hearing loss and cognitive decline in older adults.” JAMA internal medicine 173.4 (2013): 293-299.
16. Thomson, Rhett S., et al. “Hearing loss as a risk factor for dementia: A systematic review.” Laryngoscope investigative otolaryngology 2.2 (2017): 69-79.
17. Loughrey, David G., et al. “Association of age-related hearing loss with cognitive function, cognitive impairment, and dementia: a systematic review and meta-analysis.” Jama Otolaryngology–head & Neck Surgery 144.2 (2018): 115-126.
18. Ford, Andrew H., et al. “Hearing loss and the risk of dementia in later life.” Maturitas 112 (2018): 1-11.
19. Livingston, Gill, et al. “Dementia prevention, intervention, and care.” The Lancet 390.10113 (2017): 2673-2734.
20. Davis, Adrian, et al. “Acceptability, benefit and costs of early screening for hearing disability: a study of potential screening tests and models.” HEALTH TECHNOLOGY ASSESSMENT-SOUTHAMPTON- 11.42 (2007).
21. Amieva, Hélène, et al. “Self‐reported hearing loss, hearing aids, and cognitive decline in elderly adults: A 25‐year study.” Journal of the American Geriatrics Society 63.10 (2015): 2099-2104.
22. Hartley, David, et al. “Use of hearing aids and assistive listening devices in an older Australian population.” Journal of the American Academy of Audiology 21.10 (2010): 642-653.