Hearing Loss Associated with Higher Incidence of Dementia

What role does hearing loss have on cognitive decline?

Bottom line
While all 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.

Background: Dementia and hearing loss are both highly prevalent neurologic conditions in older adults, each having considerable impact on quality of life. 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. 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.

Study design: A systematic review was conducted in 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.

Synopsis: 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 (SSW) test. Dementia was most often defined using the Mini Mental State Exam (MMSE).

Confounding variables such as cardiovascular risk factors were measured, and family history of dementia was only evaluated in one study. Overall, the methods used by studies to ascertain hearing loss, cognitive status, and other variables are valid, making their evaluation appear reliable.

Citation: Thomson RS, Auduong P, Miller AT, Gurgel RK. Hearing loss as a risk factor for dementia: A systematic review. Laryngoscope Investig Otolaryngol. Published March 16, 2017. doi:10.1002/lio2.65.