Hearing Loss and Cognitive Decline: Is There a Connection?

According to the World Health Organization, up to 360 million people in the world have impaired hearing. About 33% Americans between the ages of 65 and 74 and 47% of those 75 and older have hearing loss. People with hearing loss find it difficult to talk with others, and may not enjoy participating in social activities if they cannot hear and contribute to conversations.

Recent research suggests that untreated hearing loss may lead to or exacerbate cognitive impairment. In 2013 Frank Lin, of the Johns Hopkins University School of Medicine, published a study in the Journal of the American Medical Association, Internal Medicine showing that older adults with hearing loss were at greater risk for problems with thinking and memory than were people of the same age who had normal hearing. Nearly 2000 adults aged 75 to 84 had both their hearing and their cognitive abilities tested annually over a period of seven years. Lin found that the cognitive abilities of those with hearing loss declined up to 40% faster than other participants.

Several theories have been proposed to explain this phenomenon. One is that hearing loss causes the brain to have to work harder to make sense of what may come in as garbled auditory signals; the brain has to recognize speech and separate it from background noise. Another theory proposes that hearing loss may cause parts of the brain to atrophy, but the question is whether the hearing loss causes loss of brain volume, resulting in cognitive decline, or whether the hearing loss leads to social isolation, which then causes the decline in cognitive function. There are numerous studies which have found strong correlations between social engagement and healthy cognitive function and between social isolation and cognitive decline. Because these links are only correlational, it is possible that people who have stronger cognitive function are more likely to be socially engaged; this suggests that the social involvement aspect is not a cause, but rather a consequence, of changes in cognition.

If research can show that hearing loss leads to cognitive decline, this would provide hope for addressing one cause of this widespread problem which is becoming more prevalent as the number of older adults in the population continues to increase almost exponentially. If cognitive decline can be slowed by addressing hearing loss, it would have a major impact on public health.