Common situation affecting as much as HALF of older Americans raises dementia danger, examine finds
Losing your hearing with age could raise your risk of suffering from dementia, a study suggests.
Presbycusis, or age-related hearing loss, is a progressive form of hearing loss affecting people ages 60 to 75. It’s extremely common among older Americans, striking one in three between ages 65 and 74 and nearly half after age 75.
Recent studies have suggested presbycusis could increase the risk of cognitive decline, a precursor to dementia, by increasing brain wasting and leading to isolation. However, the exact mechanism has remained unclear.
But in a new study, researchers in China believe they have found a biological ‘bridge’ between presbycusis and cognitive decline.
They believe the key lies in what they have dubbed the functional-structural ratio (FSR), which divides activity in the brain with structural volume.
Comparing older adults with presbycusis to healthy controls, the team gave over 100 participants hearing tests and cognitive assessments, along with MRI scans to look for changes to their brain volume and structure.
The team found that people with presbycusis showed greater reductions in activity and their volume of gray matter – part of the brain’s neural tissues that control thinking, memory and decision making – in areas of the brain responsible for hearing, speech and cognition. This resulted in a lower FSR.
They also found that having a lower FSR was also associated with worse hearing and poorer memory and executive function.
Hearing loss, which affects nearly half of Americans over 75, may raise the risk of dementia, a study suggests (stock image)
The researchers believe that in the future, FSR could be used to help identify older adults at a greater risk of dementia, as it may show earlier breakdowns in brain networks linked to hearing loss.
Ning Li, lead study author of Shandong Provincial Hospital in China, said: ‘The most important takeaway is that preserving hearing health may protect brain integrity.
‘Because changes in the FSR correlate with both hearing loss and cognitive decline, this ratio could eventually serve as a biomarker—a tool for doctors to identify who is at the highest risk for dementia simply by looking at their brain scans.’
The findings come as about 7 million Americans age 65 and older are living with Alzheimer’s disease, with that figure set to nearly double by 2050.
The study, published Monday in the journal eNeuro, looked at 55 people with presbycusis and 55 healthy controls. Participants were between ages 50 and 74 with an average age of 64.
The presbycusis group consisted of 19 people with presbycusis and normal cognition and 36 people with presbycusis and dementia.
The study found decreased coupling – a reduction in coordination, communication or connection between different brain regions – in the putamen and fusiform gyrus, regions of the brain linked to hearing and speech processing, respectively.
Additionally, the precuneus and medial superior frontal gyrus, which are responsible for memory and complex thinking, showed reduced FSR.
These changes were associated with both hearing loss severity and cognitive decline. Additionally, people with lower FSR scored poorer on hearing and cognitive tests.
The researchers noted that the results show age-related hearing loss and cognitive decline share similar patterns of atrophy and cognitive decline in areas of the brain responsible for hearing, speech recognition and memory.
There were several limitations to the study, including using a small sample size and lack of data on other factors that may have influenced dementia risk, such as race, socioeconomic status and other health conditions.
