New research suggests that sensory deficits may be associated with an increased risk of developing both all-cause dementia and Alzheimer’s disease (AD) dementia.
In a study from the University of Washington School of Public Health, 2,827 individuals, age 75 or more, who had been enrolled in the GEMS study (NCT00010803) and had either vision or hearing impairment had an 11% increase in all-cause dementia risk and a 10% increase in risk of AD (P < .001). Those who had both both visual and hearing impairments had dementia and AD risk increased by 86% and 112%, respectively.
People with either impairment were 1.27 (95% CI: 1.02, 1.59) times more likely to develop dementia, and those with both were 1.70 (95% CI: 1.18, 2.45) more likely to do so. Those with a single or both impairment(s) were 1.29 (95% CI: 1.02, 1.62) and 1.69 (95% CI: 1.15, 2.49) times more likely to develop AD.
For individuals with an APOE e4 genotype, the presence of vision and hearing loss together made the association stronger, although the presence of a single impairment was no longer associated with either all-cause dementia or AD.
First author of the study, Phillip Hwang, MPH said, “These findings suggest that co-occurring hearing and vision problems in late life are strongly associated with increased risk of all-cause dementia and Alzheimer’s dementia. Impairment of more than 1 sense seems to increase risk of dementia synergistically. Assessment of visual and hearing function may help identify older adults at high risk of developing dementia.”
Another study, from the University of California, San Francisco, suggests that even mild multisensory impairments increase dementia risk. Mild impairment in multisensory functioning, measured as a 4-point difference on a 12-point multisensory impairment scale, was associated with 1.68 (95% CI:1.31, 2.01) increased risk of dementia and an annual decline of 0.24 (95%CI: 2.39, 19.37). points Modified Mini-Mental State Exam.
Participants with lower sensory function scores had significantly increased risk of both dementia and cognitive decline. Risk of dementia was nearly 7 times greater for those participants in the lowest quartile for sensory function compared with those in the highest quartile.
“Our findings suggest that testing for changes in multisensory function may help identify those at high risk for dementia,” said Willa Brenowitz, PhD, MPH, a postdoctoral researcher at the University of California, San Francisco. “Sensory function in multiple domains can be measured during routine healthcare visits using non-invasive or minimally invasive tests. In addition, some forms of hearing and vision loss can be treated or corrected, which provides potential opportunities for intervention.”
The 1,810 individuals in the latter study were age 70 to 79 and had been enrolled in the Health ABC study, who did not have dementia upon enrollment. Sight, hearing, touch, and smell were objectively assessed at years 3 through 5 of 10 years of follow up. Incident dementia was retrospectively assessed over 10 years using hospital and prescription records as well as Modified Mini Mental State Examination scores.
These results were presented at the Alzheimer’s Association International Conference in Los Angeles, CA, July 14-18, 2019.