hearing loss dementia research

Hearing Loss, Dementia and Cargo Cult Science

The preeminent American physicist, Richard Feynman, coined the term “cargo cult science” to describe practices that on the surface appear scientific, but upon closer scrutiny lack any of the precepts of the scientific method. A January 25th JAMA viewpoint article raises the red flag on the rise of pseudoscience in the care of older adults with dementia. The article is a clarion call for clinicians who want to provide evidence-based healthcare. 

Given the growing aging population and the well-established link between hearing loss and dementia, hearing care professionals need to maintain a strong BS-detector and remain skeptical of all articles, press releases and advertisements that tout a simple prevention or cure for cognitive decline. This, of course, includes any blanket claims that hearing aids stave off dementia.

According to the JAMA article, authored by three UC-San Francisco professors, there are several steps healthcare professionals can take to ensure patients and their family members are not bamboozled by potentially misleading claims they may encounter that masquerade as science, including awareness of the financial interests of the authors, knowing the limitations of study designs and providing honest scientific interpretation of any claims, along with associated risk and costs.  

Fortunately, several recent studies and scientifically-valid reports, many of them published in refereed journals, can help hearing care professionals avoid the pseudoscience trap when working directly with older adult who are at-risk for both hearing loss and cognitive decline.

An excellent starting point is a recent January Hearing Review piece that nicely summarizes the work of Piers Dawes and colleagues from the SENSE-Cog project. After a quick review of the July 2017 Lancet study which indicated that hearing loss is a substantial mid-life modifiable risk factor for dementia, Dawes and colleagues summarized their work which suggests that hearing aid interventions may slow (not prevent) cognitive decline. 


Hearing Loss and Dementia


Effective hearing care for patients at-risk for dementia is not confined treatment with hearing aids. Modification of cognitive tests like the Mini-Mental States Exam (MMSE) and basic pure tone audiometry also contribute to better care for older adults. Two recent peer reviewed studies provide clinicians with guidance on how these common clinical procedures (cognitive screening and hearing threshold testing) differ in patients diagnosed with hearing loss and dementia, respectively.

First, a study published in Neuropsychology and co-authored by Virginia Ramachandran and Brad Stach, the latter is a director of audiology at Henry Ford Health System in Detroit, examined the effects of hearing loss on cognitive testing. The researchers compared cognitive test results from 41 adults with hearing loss to 41 age-matched adults with normal hearing. Results showed that cognitively intact older adults with hearing loss appeared cognitively impaired on auditory-verbal memory assessment under typical administration conditions of the cognitive tests. Further, their results indicate that older adults with hearing loss are prone to scoring below average on auditory-verbal memory portions of cognitive tests and would benefit from visual modification of these tests. The authors also provided commentary on the use of hearing aids during cognitive testing.

The entire article can be accessed at this gated site.

Second, researchers at the HEARing Cooperative Research Center in Australia conducted an evidence-based review examining the accuracy of basic pure-tone audiometry in individuals diagnosed with dementia. The researchers found three studies that met their review criteria. Based on their analysis of these three studies, they determined that between 41 to 43% of adults with dementia were unable to complete standard pure tone audiometric testing. The authors provide ideas, many adapted from pediatric audiology, on how to modify test techniques to more effectively test these patients.

Considering it is estimated that about 20% of adult patients seen in an audiology clinic have dementia, clinicians need to be well-versed in how to modify basic hearing test procedures to accurately assess hearing thresholds for these individuals.

Members of the International Auditory Society can access the HEARing Cooperative study article here.