Is Visual Impairment a Risk Factor for Dementia in Women?
JAMA Ophthalmology, June 2020
Although some research shows a link between visual and cognitive impairment, robust longitudinal data are lacking. Tran et al. explored the relationship between visual status and the risk of incident dementia and found that the risk of dementia was two-to five-fold greater for visually impaired women. Severe visual impairment further amplified the risk.
This study was a secondary analysis of a prospective longitudinal cohort of women, in which the authors compared the likelihood of incident dementia or mild cognitive impairment (MCI) among women. Eligible participants were community-dwelling women (66-84 years of age) enrolled in one of two studies from the long-running Women’s Health Initiative. Visual impairment was categorized as worse than 20/40, worse than 20/80, or worse than 20/100. Visual impairment also was assessed by self-reports. Cognitive impairment was determined by clinical assessment, cognitive testing, and centralized review and adjudication. The primary outcome was probable dementia; the researchers also evaluated incident MCI and a composite end point that included incident cases of probable dementia or MCI. Main outcome measures were hazard ratios (HRs) and 95% confidence intervals (CIs) for incident cognitive impairment.
Of the 1,061 participants (mean age, 73.8 years), 206 (19.4%) had self-reported visual impairment, and 183 (17.2%) had visual impairment established objectively. After adjustment for confounding factors, 42 (4%) were classified as having probable dementia. Twenty-eight women with MCI (2.6%) did not experience progression to dementia during the study period. The mean duration of follow-up after an eye examination was 3.8 years (range, 0-7 years).
Participants with objectively determined visual impairment were more likely to experience dementia. The highest risk was in those with a visual acuity (VA) of 20/100 or worse at baseline (HR, 5.66; 95% CI, 1.75-18.37). In contrast, dementia risk was lower among those with milder visual impairment (20/80 or worse: HR, 5.20; 95% CI, 1.94-13.95; 20/40 or worse: HR, 2.14; 95% CI, 1.08-4.21). Findings for MCI risk were similar: Those with the poorest VA had the highest risk of MCI (HR, 6.43; 95% CI, 1.66-24.85).
Identifying potentially modifiable risk factors for dementia is crucial to ensure effective interventions and other support, said the authors. Further research is needed to identify people at high risk for cognitive impairment and to study the effects of ophthalmic interventions on dementia incidence and cognitive trajectories.
The original article can be found here.