Visual impairment in older women linked to increased risk of dementia
Research increasingly links vision impairment to the risk for dementia, but there are limited long-term studies that evaluate this association. A recent secondary analysis of data on older women enrolled in the Women’s Health Initiative (WHI) longitudinal cohort ancillary studies found that visual impairment may increase a person’s risk for dementia or mild cognitive impairment (MCI). The results were part of a secondary analysis, funded in part by NIA, to evaluate data on 1,061 community-dwelling older women (age 66-84 years) enrolled in the WHI Sight Examination and WHI Memory Study.
The study, published in JAMA Ophthalmology, conducted from 2000 to present, objectively measured visual impairment at three thresholds: vision worse than 20/40, 20/80, or 20/100. Researchers also measured self-reported survey responses about vision impairment. Of the 1,061 women in the study, 183 women had objective vision impairment and 206 women had self-reported vision impairment.
Researchers used regression models to examine associations of objective and self-reported visual impairment, respectively, with risk of dementia and MCI. Results indicate that the risk of dementia and MCI was greater among women with vision impairment than those without. Of note, in these women, more severe visual impairment was associated with a higher risk of cognitive impairment. The greatest risk for dementia was among women with vision impairment of 20/100 or worse at baseline, followed by 20/80 or worse, and 20/40 or worse. Self-reported visual impairment was not associated with an increase in risk for dementia.
The researchers noted several limitations of the study. Visual acuity was only measured at baseline, so researchers were unable to evaluate changes to vision over time or measure other components that affect vision, such as depth perception or the ability to distinguish between similar color shades (contrast sensitivity). Limitations also included a small sample size and a limited number of participants within the WHI study who had dementia and MCI. Additionally, the WHI Hormone Therapy Clinical Trials enrolled only women who fit specific eligibility criteria — between 50 and 79 years old, postmenopausal, and intending to reside in the area for at least 3 years — so it is unclear whether study findings can be generalized to other women or men with visual impairment. Still, findings from this analysis suggest that objective visual impairment may be a modifiable dementia risk factor. Also, they suggest that there may be value for vision screening and vision-improving treatments. Further research should explore the effect of vision interventions on women’s risk for dementia.
This research was supported in part by the NIA Intramural Research Program and NIA grants R03AG056453, RF1AG054068, P50AG005142, and P50AG047366.
These activities relate to NIA’s AD+ADRD Research Implementation Milestone 2.D, "Disease Mechanisms: Create programs in basic, translational and clinical research aimed at comprehensive understanding of the impact of sex differences on the trajectories of brain aging and disease, phenotypes of AD and ADRD risk and responsiveness to treatment." and 2.S, "Determine interrelationships (cross-sectional and longitudinal) among aging, cerebrovascular disease and risk factors, resilience factors, genetic variants, amyloid, tau, and neurodegeneration."
Reference: Tran EM, et al. Association of visual impairment with risk of incident dementia in a Women's Health Initiative population. JAMA Ophthalmology. 2020;138(6):1-10. April 16. doi: 10.1001/jamaophthalmol.2020.0959.