Scientists have long known that as we age, our brain becomes smaller. But new research from the Johns Hopkins University in Maryland suggests that older adults who suffer from hearing loss are more likely to experience a higher level of brain shrinkage at a faster rate.
To reach their findings, recently published online in the journal NeuroImage, the research team analyzed 126 participants aged between 56 and 86 years for up to a 10-year period.
During this time, participants were required to undergo yearly magnetic resonance imaging (MRI) scans for their brain changes to be tracked.
At the baseline of the study, subjects also underwent physical examinations, including hearing tests. At this point, 71 participants had normal hearing, while 51 had impaired hearing with a minimum loss of 25 decibels.
Hearing impairment 'shrinks brain faster'
After analyzing all MRIs that had been conducted over the years, the investigators found that participants who had impaired hearing at the baseline of the study experienced brain atrophy - brain shrinkage - at a faster rate, compared with subjects who had normal hearing.
Researchers found that hearing loss in older adults may be associated with faster brain shrinkage and increased brain tissue loss.
Participants with impaired hearing also lost at least an extra cubic centimeter more of brain tissue every year, compared with those who had normal hearing.
Additionally, the investigators found that impaired hearing was linked to increased brain shrinkage in certain areas, including the superior, middle and inferior temporal gyri. These are brain structures that play a part in processing speech and sound.
But Frank Lin, of the schools of medicine and public health at Johns Hopkins University and lead author of the study, says it is not surprising that these particular brain structures were affected.
He explains that because people with hearing loss tend to use speech and sound less, brain structures linked to these processes are more likely to shrink due to lack of stimulation.
However, Lin notes that the middle and inferior temporal gyri are also associated with memory and cognition, and research has shown that these areas of the brain play a part in the early stages of mild cognitive impairment and Alzheimer's disease.
Address hearing loss 'sooner rather than later'
According to the National Institute on Deafness and Other Communication Disorders (NIDCD), approximately 36 million American adults report some degree of hearing loss.
Lin says their findings emphasize the importance of treating hearing loss as early as possible, adding:
"Our results suggest that hearing loss could be another 'hit' on the brain in many ways.
If you want to address hearing loss well, you want to do it sooner rather than later. 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."
The investigators say that further studies are warranted to investigate whether treating hearing loss early may reduce the risk of associated health issues.
Last year, Medical News Today reported on a study suggesting that musical training in early childhood may have a positive effect on how the brain processes sound later in life.