Hearing and vision loss combined pose colossal risk of cognitive decline

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The combination of hearing loss and vision loss is linked to an eight times higher risk of cognitive impairment, according to new research.

Investigators analyzed data on more than 5 million American seniors. Adjusted results show that participants with hearing impairment alone were more than twice as likely to also have cognitive impairment, while those with visual impairment alone were more than three times as likely to have cognitive impairment. .

However, people with dual sensory impairment (DSI) had an eight times higher risk of cognitive impairment.

In addition, half of the participants with DSI also had cognitive impairment. Of those with dementia, 16% had an ISD, compared to only about 2% of their peers without dementia.

“The results of this study may inform interventions that can support older adults with concurrent sensory and cognitive impairments,” said lead author Esme Fuller-Thomson, PhD, professor in the Factor-Inwentash School of Social Work at the University of Toronto. Medscape Medical News.

“Special consideration should be given to people aged 65 to 74 who have severe hearing and/or visual impairment [because]if the relationship to dementia proves causal, such interventions have the potential to mitigate the development of cognitive impairment,” said Fuller-Thomson, who is also director of the Institute for Life Course and Aging and a professor in the Department of Family and Community Medicine and Faculty of Nursing, all at the University of Toronto.

The results were published online May 2 in the Journal of Alzheimer’s Disease Reports.

Sensory isolation

Hearing and visual impairments increase with age; an estimated one-third of American adults between the ages of 65 and 74 suffer from hearing loss and 4 percent suffer from visual impairment, the investigators note.

“The link between dual hearing loss and vision loss and mental health issues such as depression and social isolation has been researched extensively, but we were very interested in the link between dual sensory loss and cognitive issues,” Fuller-Thomson said.

Additionally, “there have been several studies over the past decade linking hearing loss to dementia and cognitive decline, but less attention has been paid to cognitive problems in people with ISD, although this group be particularly isolated,” she said.

Existing research on DSI suggests an association with cognitive decline; current investigators have sought to expand upon this earlier work.

To do this, they used merged data from 10 consecutive waves from 2008 to 2017 of the American Community Survey (ACS), which was conducted by the US Census Bureau. The ACS is a nationally representative sample of 3.5 million randomly selected U.S. addresses and includes adults living in the community and those residing in institutional settings.

Participants aged 65 or older (n=5,405,135; 56.4% female) answered yes/no to questions regarding severe cognitive impairment, hearing impairment, and visual impairment. A proxy, such as a family member or nursing home staff member, provided answers for those unable to self-report.

Potential confounding variables included age, race/ethnicity, gender, education, and household income.

Potential mechanisms

The results showed that among people with cognitive impairment, there was a higher prevalence of hearing impairment, visual impairment and DSI than among their peers without cognitive impairment; moreover, a smaller percentage of these individuals had no sensory impairment (P

Type of sensory impairment Cognitive impairment No cognitive impairment
Hearing only 22% 10.8%
Sight only 9.9% 3.1%
ISN 16.0% 1.9%
Nothing 51.9% 84.3%

The prevalence of ISD increased with age, from 1.5% among respondents aged 65-74 to 2.6% among those aged 75-84 and 10.8% among those aged 85 and more.

People with higher levels of poverty also had higher levels of DSI. Among those who had not completed high school, the prevalence of DSI was higher than among high school or college graduates (6.3% versus 3.1% and 1.85, respectively).

After controlling for age, race, education and income, the researchers found “substantially” higher risks of cognitive impairment in people with sensory impairment than in those without sensory impairment.

Type of sensory impairment Odds ratio for cognitive impairment (95% CI)
Hearing only 2.66 (2.64 – 2.68)
Sight only 3.63 (3.59 – 3.67)
ISN 8.16 (8.07 – 8.25)

“The magnitude of the odds of cognitive impairment by sensory impairment was highest for the youngest cohort (65 to 74 years old) and lowest for the oldest cohort (85 years and older),” the researchers write. . Among participants in the youngest cohort, there was a “dose-response relationship” for those with hearing impairment only, visual impairment only, and ISD.

Type of sensory impairment Odds ratio (95% CI)
Hearing only 3.45 (3.40 – 3.50)
Sight only 5.16 (5.06 – 5.25)
ISN 14.24 (13.94 – 14.53)

Because the study was observational, it “does not provide enough information to determine the reasons for the observed link between sensory loss and cognitive problems,” Fuller-Thomson said. However, there are “several potential causal mechanisms [that] warrant future research.

The “sensory deprivation hypothesis” suggests that DSI could lead to cognitive deterioration due to decreased auditory and visual input. The “Resource Allocation Hypothesis” posits that older adults with hearing or visual impairment “may use more cognitive resources to accommodate sensory deficits, allocating fewer cognitive resources to higher-order memory processes,” write the authors. researchers. Hearing loss “may also lead to social disengagement in older adults, accelerating cognitive decline due to isolation and lack of stimulation,” they add.

Reverse causation is also possible. According to the “cognitive load on perception” hypothesis, cognitive decline can lead to decreased hearing and vision due to “decreased resources for sensory processing”.

Moreover, the association may be non-causal. “The ‘common cause hypothesis’ theorizes that sensory impairment and cognitive impairment may be due to shared age-related central nervous system degeneration … or frailty,” Fuller-Thomson said.

Parallel results

The results are similar to those of a study by Phillip Hwang, PhD, Department of Anatomy and Neurobiology, Boston University School of Medicine, Massachusetts, and colleagues that was published online May 5 in Open JAMA Network.

They analyzed 8-year follow-up data from 2,927 study participants for cardiovascular health (mean age, 74.6 years; 58.2% female).

Compared to no sensory impairment, DSI was associated with an increased risk of all-cause dementia and Alzheimer’s disease (AD), but not vascular dementia.

Type of dementia Relative risk (95% CI) P-value
All causes 2.60 (1.66 – 2.06)
AD 3.67 (2.04 – 6.60)
Vascular 2.03 (1.00 – 4.09) .05

“Future work in health care guidelines may consider incorporating screening for sensory impairments in older adults as part of dementia risk assessment,” Nicholas Reed, AuD, Johns Hopkins University Bloomberg School of Public Health, and Esther Oh, MD, PhD, Johns Hopkins University School of Medicine, Baltimore, Maryland, write in an accompanying editorial.

Accurate testing

Commenting on the two studies for Medscape Medical NewsHeather Whitson, MD, professor of medicine (geriatrics) and ophthalmology and director of the Duke Center for the Study of Aging and Human Development, Durham, North Carolina, said the two “further strengthen the evidence base, which has really converged in recent years to argue that there is a link between sensory health and cognitive health.”

However, “we still don’t know if hearing/vision loss causes cognitive decline, although there are plausible ways that sensory loss affects cognitive abilities such as memory, language and executive functions,” she said.

Whitson, who was not involved in the research, is also co-director of the Duke/UNC Alzheimer’s Disease Research Center, Duke University School of Medicine and Durham VA Medical Center.

“The big question is whether we can improve patients’ cognitive performance by treating or adapting their sensory impairments,” she said. “If safe and doable things like hearing aids or cataract surgery improve cognitive health even a little, that would be a huge benefit to society because sensory loss is very common and there are many treatment options. “, added Whitson.

Fuller-Thomson emphasized that practitioners should “consider the full impact of sensory impairment on cognitive testing methods, as auditory and visual testing methods may not consider hearing and visual impairments.”

Thus, “when performing cognitive tests on older adults with sensory impairments, practitioners should ensure that they communicate audibly and/or use visual speech cues for the hearing impaired, eliminating elements cognitive tests that rely on vision for people with low vision, and using physical cues for people with hearing impairment or dual sensory impairment, as this can help increase test accuracy and avoid confusion,” said she declared.

The study by Fuller-Thomson et al was funded by a donation from Janis Rotman. His investigators have not reported any relevant financial relationships. The study by Hwang et al was funded by contracts from the National Heart, Lung, and Blood Institute, the National Institute of Neurological Disorders and Stroke, and the National Institute on Aging. Hwang does not report any relevant financial relationships. Revelations from other investigators are listed in the original article. Reed received grants from the National Institute on Aging while conducting the study and served on Neosensory’s advisory board outside of submitted work. Oh and Whitson report no relevant financial relationship.

J Alzheimers Dis Rep. Published online May 2, 2022. Full article

JAMA Netw Open. Published online May 5, 2022. Full article, Editorial

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