A study looks at the impact of having both hearing and vision impairment on the chances of developing dementia.
Researchers have linked hearing impairment and vision impairment individually to an increased chance of developing dementia. However, a new study finds that an individual’s chances of developing dementia are significantly higher when they have both conditions.
The risk of developing dementia increases by 86% for individuals who have both hearing and visual impairment.
“Evaluation of vision and hearing in older adults may predict who will develop dementia and Alzheimer’s. This has important implications for identifying potential participants in prevention trials for Alzheimer’s disease, as well as whether treatments for vision and hearing loss can modify risk for dementia.”
– Study lead author Phillip H. Hwang, University of Washington
Re-purposing a previous study’s data
The research, “Dual sensory impairment in older adults and risk of dementia from the GEM Study,” appears in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring.
According to the study, some 33% of people aged 70 and older experience hearing loss, and vision loss affects about 18% of people in this age group. Since these conditions worsen with age, researchers think that a correlation exists between the advance of these conditions and the loss of a person’s functionality and mortality.
Previous research found a less obvious connection between hearing or visual loss and the onset of dementia.
The two leading theories indicate that either these specific impairments result from similar physical processes that cause dementia, or that hearing and visual loss lead to an increasing sense of social isolation, depression, and physical inactivity, each of which may lead to dementia.
The new study looks at the impact of having both conditions together. It refers to this combination as “dual sensory impairment.” According to the study:
“Although most prior studies have focused on impairments in hearing and vision individually, the impact of having combined hearing and visual impairment, or dual sensory impairment (DSI), on dementia risk is unclear.”
To investigate the impact of DSI on developing dementia, the researchers analyzed data collected by the Gingko Evaluation of Memory (GEM) study, a double‐blind randomized‐controlled trial investigating the value of Ginkgo biloba for preventing dementia in older people.
The GEM study involved adults aged 75 or older who, at the outset of the study, had normal cognitive function, or at most, mild dementia. The researchers studied the participants for 8 years.
In addition to collecting self-reported data regarding the individuals’ hearing and vision, follow-up examinations of participants assessed the development of dementia.
DSI and the risk of dementia
The final data set that Hwang and his colleagues studied consisted of 2,051 individuals. Of these, 1,480 people had neither hearing nor visual loss. 14.9% reported visual impairment, and 7.8% reported hearing loss. Just 5.1%, or 104 individuals, had DSI.
Compared to participants who did not have hearing or visual loss, those reporting DSI were more likely to be male, have other comorbidities, and describe themselves as smokers and drinkers.
The GEM study’s follow-up examinations revealed the following likelihoods of developing dementia:
- 14.3% of those without any reported hearing or vision loss developed dementia.
- 16.9% of those reporting a single impairment developed dementia.
- 28.8% of those with DSI developed dementia.
People with both hearing and visual loss were nearly twice as likely to develop dementia as those without such impairments.
However, according to the results, the increased risk of dementia for an individual with DSI is only somewhat related to the severity of hearing and visual impairment.
While those classified as having a high level of DSI are at the greatest risk of developing dementia, those with lower DSI levels also have a significantly higher risk of dementia.
