The Association of Cognitive and Visual Function in a Nationally Representative Study of Older Adults in India

Abstract

Introduction: Due to population aging, India is poised to experience a large increase in the burden of both dementia and vision impairment (VI). Prior studies from other settings suggest that VI may be a modifiable risk factor for cognitive decline and dementia. However, to date, no studies have examined the association of impaired visual acuity and cognition in India. Methods: A total of 3,784 participants in wave 1 of the population-based Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India underwent visual acuity testing and a cognitive test battery. Multivariable linear regression was used to model the cross-sectional associations of mild (<6/12–6/16), moderate (<6/18–6/60), and severe visual acuity impairment/blindness (<6/60) with cognitive performance scores corresponding to total cognition, orientation, memory, language/fluency, executive function, and informant-reported cognitive status. Models were adjusted for demographic, socioeconomic, and health characteristics. Results: The weighted percentage of participants with any VI was 52.6%. VI was independently associated with lower cognitive scores across all domains, even after adjustment for known dementia risk factors. In fully adjusted models of total cognition (mean score: 130.7), mild, moderate, and severe VI/blindness were associated with a significant change of −3.5 (95% CI: −6.3, −0.6), −8.2 (95% CI −10.5, −5.6), and −16.8 (95% CI −22.3, −11.3) units, respectively. A dose-response association between level of VI and cognitive function was observed for all cognitive outcomes except for language/fluency domain scores. Associations were robust when cognitive tests dependent on visual function were excluded. Across each fully adjusted model of total, domain-specific, and informant-reported cognitive performance, moderate VI was equivalent to 5–9 years of cognitive aging. Discussion/Conclusion: This study illustrates that VI is cross-sectionally associated with lower cognitive performance, largely in a dose-response pattern, across various cognitive domains in the Indian population. These findings are important for informing future longitudinal and interventional studies.

Prevalence and predictors of vision impairment among older adults in India: evidence from LASI, 2017–18

“…On the contrary, the prevalence of diabetes among older individuals was negatively associated with VI in our study which is at variance with previous studies showing a positive association of diabetes mellitus with VI and blindness [ 49 , 50 ]. This unexpected finding may be explained by the fact that older adults who self-reported diagnosis of diabetes might have received routine medical care and eye exams and utilized vision enhancing interventions like eyeglasses and cataract surgery as well as were more likely to have proper compliance with medicine [ 51 ]. However, since diabetes is known to be an important cause of VI and blindness in India and across the globe [ 52 ], the current finding requires further investigation.…”

Refractive error and Alzheimer's disease: A bidirectional Mendelian randomization study

“…A previous study reported that 80% of visual impairment can be corrected [7] . Refractive error is the most common visual impairment and presents a growing incidence; moreover, it is a risk factor for Alzheimer's disease.…”

Association between vision and cognitive function among community-dwelling older adults in Selangor, Malaysia

“…MCI prevalence in low and middle-income countries ranged from 0.3% to 63.3%, while the prevalence in Malaysia ranged from 15.8% to 21.1% [11] . Reduced vision is associated with cognitive decline [12][13][14][15][16][17] . The sensory deprivation hypothesis states that a decline in visual perception over time leads to gradual neural degradation and consequently reduced cognition [18] .…”