Hearing Loss Linked to Dementia
A new study from researchers at Johns Hopkins confirms an association between hearing loss and cognitive decline. Participants who had some hearing loss at the outset of the study had a 24% higher risk than those with normal hearing for developing cognitive impairment over the course of the study. This study followed 1,984 older individuals (average age of 77) who had a range of hearing ability for six years. Their hearing and cognitive functioning were tested at regular intervals during this time.
The study data showed not only that those with hearing loss were more likely to decline cognitively, but also that the amount of the decline was correlated with the extent of the hearing loss. This study builds the findings of another study published in 2011 which followed over 600 people for 11 years and which concluded that hearing loss was associated with cognitive decline.
Explaining the Link Between Hearing Loss and Cognitive Decline
Researchers do not know what the link is between hearing loss and dementia. Several theories have been put forth:
- Social isolation and lack of stimulation. Those with significant hearing loss have a difficult time understanding others and tend to withdraw. It is thought that the ensuing isolation and lack of engagement might impair one’s ability to think.
- “Cognitive Overload”. People with hearing loss have to so concentrate hard to understand what is being said, that their brains might not be able to process the information received in the usual way. The processing may be less accurate. There is some evidence through MRI studies that people with hearing loss rely on the prefrontal cortex to process the language, a part of the brain that is not normally used to process information.
- A biologic decline in the brain that affects both hearing and cognition. The loss in hearing and the loss in cognitive ability may be tied to a common degenerative process. To date, no one has identified what that process might be.
Dr. Frank Lin, the primary researcher of both these studies, is now preparing a follow up study to determine if the correct use of assistive devices, including hearing aids, loops, and FM transmitters, can slow the cognitive decline.
People who are experiencing cognitive decline should get their hearing checked. If they have a hearing loss, they should use a hearing aid or other device to counter the hearing loss, and to possibly improve their cognitive functioning.