Eliane Schochat1, Renata Filippini1, Frank Musiek
1 Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR
Age-related hearing loss (ARHL) is projected to be within the top 15 leading causes of burden of disease by 2030 (Mathers & Loncar, 2006 ). Acquired hearing loss can negatively affect mental health, participation in interpersonal relations, and health-related quality of life. Population-based studies suggest that hearing loss is associated with more rapid cognitive and physical aging (Lin et al., 2013). The 2015 National Institute on Aging workshop, “Sensory and motor dysfunction in aging and Alzheimer’s disease”, in the United States, reported that age-related sensory loss, including hearing loss, is associated with dementia and falls.
In addition, the elderly frequently have speech-comprehension complaints that could not be justified by their hearing thresholds or the adaptation to hearing devices is unsuccessful despite using algorithms and settings appropriated to their hearing loss. In these cases, deficits in the central nervous system functions and structures should also be suspected. Therefore, hearing deficits, both central and peripheral, are important factors to consider while investigating communication issues in the elderly.
It has been suggested that the allocation of extra cognitive resources to deal with challenging auditory perception – not only as consequence of hearing loss but also of hearing under environmentally adverse conditions – could accelerate the neurocognitive decline during aging. A few studies demonstrated positive correlation between cognitive processing and speech processing, and patients with several variations of dementia have been shown to have auditory processing deficits (Hardy et al, 2016). Humes et al. (2013) observed significant correlation between general sensory processing (visual, auditory and tactile) and age, but not for cognitive processing and age. They conclude that sensory deficits, especially if there is an association of two or more modalities, may lead to the cognitive deficits observed in older individuals.
One example of this sensory-cognitive interaction is the correlation between cognitive performance in working memory tests and some auditory processing skills, such as speech-in-noise perception, pitch pattern frequency and dichotic listening tests Regarding speech-in-noise perception, Pichora-Fuller (2003) hypothesized that the efficient operation of the working-memory system becomes compromised, negatively affecting the comprehension of spoken language as a consequence of hearing difficulties and the effort required to listen in the presence of noise. Dichotic listening performance has also been associated with working memory skills, especially in the forced-left condition that requires a great cognitive engagement produced by competition with “right ear advantage” (Hugdahl, 2003). Studies have also reported an association between sensory declines, such as ARHL and auditory processing disorders, and cognitive declines, such as mild cognitive impairment and dementia (Wayne and Johnsrude, 2015).
Although the positive effect of education on cognitive skills is currently widely accepted, the impact of education on auditory processing has not yet been evaluated. This topic is reasonable given the studies demonstrating sensory-cognitive interactions in the aging process. From a neurophysiological perspective, this sensory-cognitive interaction is based on the significant contribution of the top-down mechanisms of auditory perception, which is supported by the involvement of multi-modal association areas of the cortex in response to simple sounds and the contribution of the efferent auditory system in modulating some auditory processing skills, such as binaural processing (Moore, 2012). Thus, because both sensory and cognitive factors are strongly involved, we might predict that, as long as education leads to improved cognitive performance or affects the course of cognitive decline, it will also be possible to observe improved performance on tests involving auditory processing skills.
Murphy et al. (2016), investigated the performance of middle-aged and elderly people with different levels of formal education on auditory processing tests. A total of 177 adults with no evidence of cognitive, psychological or neurological conditions took part in the research. The participants completed a series of auditory tests, including dichotic digits, frequency pattern and speech-in-noise. A working memory test was also performed to investigate the extent to which auditory processing and cognitive performance were associated. The results demonstrated positive but weak correlations between years of schooling and performance on all of the tests applied. The factor “years of schooling” was also one of the best predictors of frequency pattern and speech-in-noise test performance. Additionally, performance on the working memory, frequency pattern and dichotic digit tests also correlate, which suggests the influence of educational level on auditory processing performance is related to cognitive demand of the auditory processing tests rather than auditory sensory aspects per se. Longitudinal research is required to investigate the causal relationship between educational level and auditory processing abilities.
Additional studies must investigate influence of the education level using auditory electro-physiological evaluations that are more complex and determine the extent to which educational levels might show auditory processing deficits. It is also important to add some kind of cognitive test into the auditory test battery.
- Hardy CJ, Marshall CR, Golden HL, Clark CN, Mummery CJ, Griffiths TD, et al. Hearing and dementia. J Neurol 2016.
- Hugdahl, K. (2003). “Dichotic listening in the study of auditory laterality,” in The Asymmetrical Brain, eds K. Hugdahl and R. J. Davidson (Cambridge: MIT Press), 441–476.
- Humes LE, Kewley-Port D, Busey TA, Craig J. Are age-related changes in cognitive function driven by age-related changes in sensory processing? Atten Percept Psychophys 2013; 75(3): 508-524.
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- Mathers C. D. , & Loncar D . ( 2006 ). Projections of global mortality and burden of disease from 2002 to 2030 . PLoS Medicine , 3 , e442 .
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- Murphy, CFB; Rabelo, CM; Silagi, ML; Mansur, LL; Schochat, E (2016) -Impact of Educational Level on Performance on Auditory Processing Tests. Front. Neurosci., 10 March 2016 | https://doi.org/10.3389/fnins.2016.00097
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- Wayne, R. V., and Johnsrude, I. S. (2015). A review of causal mechanisms underlying the link between age-related hearing loss and cognitive decline. Ageing Res Rev. 23, 154–166. doi: 10.1016/j.arr.2015.06.002