Hearing loss is considered the most common disability among elderly people. In the United States, it affects approximately a quarter of those between the ages of 65 and 74, and almost half of those who are older than 75. 

According to a preliminary study set to be presented at the American Academy of Neurology's 70th Annual Meeting in Los Angeles, hearing impairment may also be associated with memory loss. 

The study was led by Rodolfo Sardone, who is from the National Institute of Health, Maryland, and University of Bari, Italy, and examines how age-related hearing loss is linked to the risk of developing mild cognitive impairment (MCI), which can cause issues related to judgment, language, and memory. This is of particular significance as MCI can increase the risk of dementia and Alzheimer's disease. 

Two types of hearing loss were taken into account for the study. Peripheral hearing loss is caused by problems in the functioning of the inner ear and hearing nerves, which leave patients unable to hear anything. Central hearing loss is caused by problems in the brain's ability to process sounds. Those diagnosed with it may usually say, "I can hear, but I can't understand."

A total of 1,604 people participated in the study, of which 26 percent had a peripheral hearing loss, 12 percent had a central hearing loss, and 33 percent were diagnosed with mild cognitive impairment. With an average age of 75, the participants were tested on hearing, thinking and memory skills.  

Findings of the study showed 75 percent of those with central hearing loss (144 out of 192 people) had mild cognitive impairment, while the figure was 60 percent for those without hearing loss (365 out of 609 people). Researchers observed people who had lower scores on a test that measured levels of understanding speech also had lower scores on tests which measured thinking and memory skills.

Sardone noted the study doesn't necessarily prove hearing loss causes memory loss, but only indicates an association between the two.

"These preliminary results suggest that central hearing loss may share the same progressive loss of functioning in brain cells that occurs in cognitive decline, rather than the sensory deprivation that happens with peripheral hearing loss," he said. "It's a problem with perception. Tests of hearing perception should be given to people who are older than 65 and also to people with cognitive impairment."

There has been a growing body of evidence showing an association between hearing loss and cognitive impact. In 2013, John Hopkins researchers found those who suffered from hearing loss showed a considerably faster mental decline than those without it. Dr. Frank Lin, who led the study, published another article the following year where researchers observed shrinkage and tissue loss in the brain that may have been accelerated by hearing loss.

“If hearing loss is potentially contributing to these differences we’re seeing on MRI, you want to treat it before these brain structural changes take place,” Dr. Lin said, urging both patients and medical establishments to destroy the stigma around hearing loss.