Treating Hearing Loss May Slow Down Decline in Cognitive Functioning
Several recent studies have suggested that hearing loss is tied to cognitive decline. For instance, a 2013 study conducted by Frank Lin, an otologist at Johns Hopkins University in Baltimore, showed that adults with moderate hearing loss (severe enough to interfere with conversation) were 24% more likely than adults with normal hearing to see their cognitive abilities decline over the span of 6 years. In that study, the average age of the participant was 77, and the cognitive abilities measured included concentration, memory and the ability to plan.
Another study, completed in 2015 at the University of Bordeaux in France, tracked the hearing loss and cognitive functioning of 3,777 adults over a span of 25 years. Those adults who self-reported hearing loss at the beginning of the study were significantly more likely to start the program with lower cognitive functioning scores, and showed greater decline in cognitive abilities over the 25-year span than those with normal hearing.
The majority of older adults have some degree of hearing loss, so this might sound like bad news for a lot of people. Estimates vary, but in general, it’s thought that more than half of adults over 75 have hearing loss, and that rate goes up with age. But there is a bright side to all these studies – they also found that treating hearing loss might be able to slow down cognitive decline.
One very recent study from Columbia University Medical Center found that adults between the ages of 80 and 99 scored higher on tests of cognitive function if they used hearing aids when compared to adults who did not use hearing aids. They also found that overall cognitive functioning was tied to hearing ability, even if the participant did not use a hearing aid.
This finding is in agreement with the University of Bordeaux study mentioned earlier, which found that the level of cognitive decline in subjects who used a hearing aid was the same as the level of decline in subjects who had no hearing problems at all.
Since only about 15% of adults with hearing problems wear hearing aids, this means that there are lots of people who could potentially slow down their age-related loss of cognitive ability simply by treating their hearing loss.
Although scientists don’t totally understand why there is a link between hearing loss and mental functioning, there are a couple of possible explanations that researchers are considering. One explanation is that if your brain is spending up its resources just to comprehend what you are hearing, then it has less resources available for other tasks, like planning or remembering things. Another possible explanation is being hard of hearing tends to lead to social isolation: people who can’t hear conversations well can’t take part in them actively. Social isolation has been known for a long time to lead to increased likelihood of dementia, since interaction with others helps stimulate the brain.