Given the prevalence of hearing loss and cognitive decline in our aging population, establishing a link between these two conditions has been an area of staunch interest among researchers and clinicians for several years. In general, issues related to hearing loss have been garnering attention in the medical literature, as a December 2 editorial in the esteemed journal Lancet was devoted to the global burdens of untreated hearing loss across the age spectrum. This trend continued December 7 when JAMA Otolaryngology published a meta-analysis that examined this association between age-related hearing loss and various forms of cognitive decline, including dementia and Alzheimer’s disease.
A group of researchers from Ireland and the U.S. analyzed 36 observational studies comprised of more than 20,000 adult participants from 12 countries. The objective of their work was to address the following question: Is age-related hearing loss associated with an increased risk for cognitive decline, cognitive impairment and dementia? After a systematic review process, the answer to their question was “yes.”
In their meta-analysis, age-related hearing loss had significant associations with cognitive function in all ten cognitive domains of interest, including executive function, processing speed, semantic memory, episodic memory and global cognition. Unlike other similar evidence-based reviews, Loughrey and colleagues only included in their systematic meta-analysis studies that objectively measured hearing loss with pure tone audiometry. In addition, through statistical analysis, the researchers found increased risks for Alzheimer’s disease and vascular dementia were not significant.
Although the causal mechanisms linking age-related hearing loss and cognitive decline continue to remain unclear, meta-analysis of observational studies indicates that adults with hearing loss are more at-risk for developing conditions that impact their executive functioning, memory and other cognitive abilities.
According to Loughrey and colleagues, “The pattern of decline observed in this study was consistent with estimated cognitive outcomes based on behavioral and neuroimaging research. This research reports increased recruitment of short-term memory and executive functions to aid speech perception after acquired hearing loss and concomitant decline in auditory cortex regions. This situation is estimated to lead to less decline in these functions, but greater decline in episodic and semantic long-term memory owing to reallocation of cognitive resources. Consistent with this research, we observed that hearing loss was less associated with decline in executive functions and immediate recall compared with delayed and semantic memory and was increasingly less predictive of decline in attention and immediate recall among those with greater hearing loss. Furthermore, the results indicated that hearing aids may benefit short-term and semantic memory.”
Considering the abundance of data showing a non-causal link between age-related hearing loss and cognitive decline, a public health strategy emphasizing prevention through the reduction of risk factors may be more beneficial than a health care strategy that relies exclusively on costly pharmacological therapy after the diagnosis of dementia.
Otolaryngologists and audiologists, in turn, would be wise to take action in the following ways:
- Educate primary care physicians (and the public) that hearing loss in older adults is a modifiable risk factor associated with cognitive decline.
- Encourage primary care physicians to take a more active role in conducting hearing screening of older adults and refer individuals who fail the screen to see an ENT-Audiology practice.
- Per the June 2016 NASEM guidelines, offer a wider range of amplification devices, including high quality non-custom amplifiers at a lower price point.
- Audiologists are encouraged to screen for cognitive decline in older adults and make a referral to a geriatric professional who can assess and diagnose dementia.
- For patients with the diagnosis of dementia, modify the hearing loss treatment regimen to include devices and services that enable the patient with dementia to maximize their functional ability with everyday communication.
To learn more about each of these five points and how they can be implemented in your practice, contact your Fuel representative.