Hearing loss as a risk factor for dementia: A systematic review

Is your doctor proactively testing your hearing? Or is s/he just doing the status quo of nothing? You have a good chance of getting dementia, hopefully your doctor has protocols to prevent that. 

Your risk of dementia, has your doctor told you of this?

1. A documented 33% dementia chance post-stroke from an Australian study?   May 2012.

2. Then this study came out and seems to have a range from 17-66%. December 2013.`    

3. A 20% chance in this research.   July 2013.

4. Dementia Risk Doubled in Patients Following Stroke September 2018 

The latest here:

Hearing loss as a risk factor for dementia: A systematic review

Rhett S. Thomson, BA, ^{1 , 2} Priscilla Auduong, MD, ^{1 , 2} Alexander T. Miller, BS, ^{1 , 2} and Richard K. Gurgel, MD ^{1 , 2}

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Abstract

Objectives

To review evidence of hearing loss as a risk factor for dementia.

Data Sources: PubMed

Review methods: A systematic review was conducted using the PubMed database using the search terms (hearing loss OR presbycusis) AND (dementia OR cognitive decline). Initially, 488 articles were obtained. Only those studies evaluating an association between hearing loss and incident dementia or cognitive decline were included in the analysis. This resulted in 17 articles which were thoroughly evaluated with consideration for study design, method for determining hearing loss and cognitive status, relevant covariates and confounding factors, and key findings.

Results

All of the 17 articles meeting inclusion criteria indicate that hearing loss is associated with dementia or cognitive decline. The methods used among the studies for ascertaining hearing loss and dementia were notably varied. For hearing loss, peripheral auditory function was tested far more than central auditory function. For peripheral audition, pure tone audiometry was the most commonly reported method for defining hearing loss. Only a few studies measured central auditory function by using the Synthetic Sentence Identification with Ipsilateral Competing Message test (SSI‐ICM) and the Staggered Spondaic Word Test (SSW). Dementia was most often defined using the Mini Mental State Exam (MMSE). However, many studies used extensive batteries of tests to define cognitive status, often including a neuropsychologist. Confounding variables such as cardiovascular risk factors were measured in 17 studies and family history of dementia was only evaluated in 1 study. Overall, the methods used by studies to ascertain hearing loss, cognitive status and other variables are valid, making their evaluation appear reliable.

Conclusion

While each of the studies included in this study utilized slightly different methods for evaluating participants, each of them demonstrated that hearing loss is associated with higher incidence of dementia in older adults.

Level of Evidence

Level V, systematic review.

Keywords: agre‐related hearing loss, dementia, cognitive decline, Alzheimer's disease, presbycusis

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INTRODUCTION

Dementia and hearing loss are both highly prevalent neurologic conditions in older adults, each having considerable impact on quality of life.¹, ² A growing body of literature suggests that these two conditions are interrelated and that hearing loss may be a risk factor for the development of dementia in older adults.³, ⁴ Though several epidemiological studies have demonstrated this association, the causal link of how hearing loss increases the risk of developing dementia is not well understood.

Several possible means have been identified. One line of thought is based on the impact of hearing loss on cortical processing. Hearing loss increases the cognitive load, diverting cognitive resources to auditory processing at the expense of other cognitive processes such as working memory.⁵, ⁶ Another hypothesis is that hearing loss leads to social isolation, which has been shown to contribute to dementia.⁷, ⁸ The third prominent explanation is that there is a common cause to both diseases and that hearing loss is the early manifestation of the underlying pathology.⁹, ¹⁰, ¹¹ It is also possible that these proposed mechanisms are not mutually exclusive, and decline in one pathway consequentially affects the others.

Better understanding the etiology behind the connection between hearing loss and dementia could help lead to interventions that preserve cognitive function in hearing loss patients. In this way, hearing loss could serve as a potential modifiable risk factor. It is suggested that interventions delaying the onset of dementia by even one year would decrease the worldwide prevalence of dementia by 10%.¹² Thus, there is compelling motivation to pinpoint the role hearing loss has on cognitive decline. The object of this study is to further investigate this connection. This will be performed through a systematic review of epidemiological studies published on the topic. Each study will be evaluated with consideration to design, method for determining hearing loss and dementia, relevant covariates and confounding factors, key findings, and conclusion.

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