Hearing Loss Found to Be an Independent Predictor of Developing Dementia

In multiple research studies, age-related hearing loss has been independently associated with decreased cognitive function and an increased likelihood of dementia.

In 2010, there were 4.7 million people 65 years or older with Alzheimer’s disease, and that number is projected to increase to 13.8 million by 2050. Hearing loss occurs in as many as two-thirds of all individuals 60 or older, and more than 80 percent of those above the age of 85 have a hearing loss. Both cognitive impairment and hearing loss are two conditions that are associated with aging, and there is likely overlap between auditory and cognitive decline.

The purpose of the study “Relationship of Hearing Loss and Dementia: A Prospective, Population-Based Study” was to determine whether baseline hearing loss increases cognitive decline and risk of dementia. All permanent residents of Cache County, UT, aged 65 years and older were recruited to the study — a total of 5,092 individuals — and were enrolled and evaluated for cognitive performance.

Hearing loss was found to be an independent predictor of developing dementia. Of those with hearing loss, 16.3 percent of test participants developed dementia, compared with 12.1 percent of those without hearing loss. Mean time to dementia was 10.3 years in the hearing loss group versus 11.9 years for the non-hearing loss group. The findings of this study suggest that hearing impairment may be a marker for cognitive dysfunction in adults aged 65 and older — which compares favorably with other studies suggesting the same.

Cardiovascular risk factors, including diabetes, smoking, high cholesterol, and hypertension, remained a part of this analysis because these are risk factors that have also been associated with hearing loss, dementia, or both. Only two of those risk factors — diabetes and smoking — showed that hearing loss remained an independent risk factor for dementia. The participants’ average age was 75.4 years.

Central auditory processing appears to be affected by dementia. A dysfunction in this area is found in patients with mild memory impairment and is a precursor to Alzheimer’s. Under conditions where auditory perception is difficult, prior research has shown that more cognitive resources are dedicated to auditory perceptual processing, usually to the detriment of other cognitive processes such as working memory. Working memory is thought to be an important part of conversing and hearing speech in noise.

The increased cognitive load, social isolation, and neurobiology of hearing loss may not be mutually exclusive in the hearing process, as each may contribute in some way to cognitive failures. A clear understanding of the extent of hearing loss and how to effectively treat it may yield a wider range of benefits than previously realized. Better hearing health means a higher quality of life for patients, their families, and their friends — and that means good things for our entire local community.