Cognitive decline in elderly more likely with poor hearing

By Sally Robertson, B.Sc.Jan 29 2013

Older adults with hearing loss may be at an increased risk for cognitive decline and cognitive impairment, report researchers.

A study of 1984 individuals (aged a mean of 77.4 years) from the Health Aging, and Body Composition (ABC) study showed that those who had hearing loss at baseline had significantly greater annual rates of decline in cognitive scores over the following 6 years, compared with those with normal hearing.

Furthermore, those with baseline hearing loss had a significantly greater likelihood for developing cognitive impairment than those with normal hearing at baseline.

"Determining if hearing loss is independently associated with cognitive decline is an important first step toward understanding whether the use of hearing rehabilitative interventions could help mitigate cognitive decline," say Frank Lin (Johns Hopkins Center on Aging and Health, Baltimore, Maryland, USA) and team.

As reported in JAMA Internal Medicine, cognitive assessment of the participants using the Modified Mini-Mental State Examination (3MS) and the Digit Symbol Substitution (DSS) test showed that none of the study population had cognitive impairment (3MS score ≥80) at baseline.

Among those who had hearing loss (as defined by World Health Organization criteria), the mean 3MS and DSS scores at baseline were a significant 0.75 and 0.92 points lower, respectively, than in those with normal hearing.

During the 6-year follow-up, those with hearing loss had significant 41% and 32% greater annual reductions in mean 3MS and DSS scores, respectively, than those without hearing loss at baseline.

Further analysis showed that a total of 609 cases of incident cognitive impairment occurred during the follow-up period, and individuals who had hearing loss at baseline had a 24% increased risk for incident cognitive impairment compared with those who did not.

"Communication impairments caused by hearing loss can lead to social isolation and loneliness in older adults, and epidemiologic and neuroanatomic studies have demonstrated associations between loneliness and cognitive decline or dementia," note the researchers.

Moreover, "studies demonstrating that under conditions where auditory perception is difficult (ie, in the case of hearing loss), greater cognitive resources are dedicated to auditory perceptual processing, to the detriment of other cognitive processes such as working memory."

The team says further research is needed to investigate the mechanisms underlying the association between hearing loss and cognitive decline and whether such pathways would be amenable to hearing rehabilitative interventions.

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