New Study Explains Why Hearing Loss is Linked to Dementia

Hearing loss has a long connection to an increased risk of dementia, although the link between the two has baffled scientists for years. Now, a new study may finally have an answer. When you lose this key sense, your brain works harder to detect sound. Researchers have discovered that these subtle brain changes appear to contribute to dementia onset.

Using a mix of hearing tests and MRI scans of the brain, scientists in California have detected several brain regions affected by hearing impairment. Amongst the changes are microstructural differences in the auditory areas of the temporal lobe and areas of the frontal cortex in charge of speech and language processing.

Additionally, the team found changes in areas of the frontal cortex involved with executive functioning — the ability to perform complex cognitive tasks such as planning, paying attention, and multitasking.

“These results suggest that hearing impairment may lead to changes in brain areas related to processing of sounds, as well as in areas of the brain that are related to attention. The extra effort involved with trying to understand sounds may produce changes in the brain that lead to increased risk of dementia,” says principal investigator Linda McEvoy, a professor at the University of California-San Diego and senior investigator at the Kaiser Permanente Washington Health Research Institute, in a media release.

“If so, interventions that help reduce the cognitive effort required to understand speech — such as the use of subtitles on television and movies, live captioning or speech-to-text apps, hearing aids, and visiting with people in quiet environments instead of noisy spaces — could be important for protecting the brain and reduce the risk of dementia.”

McEvoy designed and led the study while at UC San Diego, in collaboration with Reas and UC San Diego School of Medicine investigators who gathered data from the Rancho Bernardo Study of Health Aging, a longitudinal cohort study of residents of the Rancho Bernardo suburb in San Diego that launched in 1972. For this analysis, 130 study participants underwent hearing threshold tests in research clinic visits between 2003 and 2005 and subsequently had MRI scans between 2014 and 2016.

The results of the study show that hearing impairment is associated with regionally specific brain changes that may occur due to sensory deprivation and to the increased effort required to understand auditory processing stimulations.

“The findings emphasize the importance of protecting one’s hearing by avoiding prolonged exposure to loud sounds, wearing hearing protection when using loud tools and reducing the use of ototoxic medications,” said co-author Emilie T. Reas, Ph.D., assistant professor at the UC San Diego School of Medicine.

Article originally appeared on Neuroscience News