Hearing Loss and Dementia in Older Adults

The relationship between hearing and cognition is a highly discussed and researched topic in the field of audiology. In a recent article in Canadian Audiologist (2023), Kathy Pichora-Fuller, PhD, reviews what we do and do not know about hearing and cognition as well as expected advances in research in 2023. She reminds readers that an evidence-based practice (EBP) approach will be the best strategy to examine a true relationship between hearing and cognition.

An EBP approach develops a focused clinical question and considers patient characteristics and perceptions, clinical expertise, and currently-available research to answer the question. In her article, Dr. Pichora-Fuller addresses two primary questions:

1. Does the presence of hearing loss in older adults predict later development of dementia?
2. Does hearing health care modify the risk for dementia in older adults?

Regarding the first question, Dr. Pichora-Fuller reminds readers that correlation does not prove causation. A relationship between hearing loss and dementia could be valid or also could be related to other medical issues. Long-standing research in older adults supports an association between hearing loss and performance on cognitive tests (e.g., Lindenberger and Baltes, 1994; Baltes and Lindenberger, 1997). However, there is no compelling evidence to suggest hearing loss independently affects the development of dementia in older adults (Powell et al, 2021; Marinelli et al, 2022).

More specifically, in one study on 1,200 patients, Marinelli et al (2022) reported a significant relationship between pure-tone thresholds and performance on cognitive tests, but no relationship between pure-tone thresholds and incident dementia, regardless of hearing aid use. Interestingly, however, patient-reported hearing difficulties were associated with the development of dementia. These findings highlight the complex nature of hearing loss and cognition, the potential for varied findings across test measures, and the need for more research in this area.

To address the second question, Dr. Pichora-Fuller begins by reminder readers that, in the widely cited Livingston et al (2020) review, hearing loss was listed as only one of the 12 potentially modifiable risk factors for dementia, and the list of factors will likely continue to grow. Because this is a review article, it does not provide clear evidence that the factors are actually proven to modify the risk of dementia. Actual risk will depend on an individual’s other health conditions, social determinants, everyday environments, and stage of aging.

There is some emerging evidence in a recent meta-analysis and systematic review (Yeo et al, 2022); researchers found that hearing aid users had lower hazards of cognitive decline relative to non-users as well as a three percent improvement in cognitive test scores after the use of hearing aids. However, given the varied methodologies used in the study, there is still much to learn.

Dr. Pichora-Fuller suggests the need for well-controlled randomized controlled trials (RCT) to examine the potential for varied results across:

1. Populations studied including various degrees of hearing loss, baseline cognition, and social determinants of health
2. Interventions involving hearing aids, cochlear implants, and other rehabilitative approaches
3. Group randomization strategies (i.e., composition of control groups including patients with comorbidities; and
4. Cognitive and other outcome measures.

Some of these issues with the existing evidence will be addressed by the Aging and Cognitive Health Evaluation in Elders (ACHIEVE; NCT03243422) RCT, which should be published in 2023 (Deal et al, 2018).

Regardless of the future research findings related to hearing loss and cognition, audiologists will need to continue to use EBP to select appropriate clinical test measures as well as evidence shared with patients during counseling. In addition, given the wide array of potential difficulties associated with aging, audiologists will need to work in interprofessional teams to promote health aging and ensure integrated care.

References

Baltes P, Lindenberger U. (1997) Intellectual functioning in old and very old age: crosssectional results from the Berlin Aging Study. Psychol Aging 12(3):410–432.

Deal JA, Goman AM, Albert MS, et al. (2018) Hearing treatment for reducing cognitive decline: design and methods of the Aging and Cognitive Health Evaluation in Elders randomized controlled trial. Alzheimer’s Dementia Transl Res Clin Interv 4:499–507.

Lindenberger U, Baltes PB. (1994) Sensory functioning and intelligence in old age: a strong connection. Psychol Aging 9(3):339–355.

Livingston G, Sommerlad A, Orgeta V, et al. (2017) Dementia prevention, intervention, and care. Lancet 390(10113):2673–2734.

Marinelli JP, Lohse CM, Fussell WL, et al. (2022) Association between hearing loss and development of dementia using formal behavioral audiometric testing within the Mayo Clinic Study of Aging (MCSA): a prospective population-based study. Lancet Healthy Longy 3 (12):e817–e824.

Pichora-Fuller K. (2023) Is hearing loss in older adults predictive of later development of dementia and does hearing care modify dementia risk? Canadian Aud 10(1):1–26.

Powell DS, Oh ES, Lin FR, Deal JA. (2021) Hearing impairment and cognition in an aging world. J Assoc Res Otolaryngol 22(4):387–403

Yeo BSY, Song HJJM, Toh EMS, et al. (2022) Association of hearing aids and cochlear implants with cognitive decline and dementia: a systematic review and meta-analysis. JAMA Neurol. In press.