In 2015, visual impairment affected over 253 million individuals worldwide (Ackland, Resnikoff, & Bourne, 2017). There are many possible downstream effects of such impairment, including negative lifestyle changes and psychological and physical decline (Brody, 2021). Recent research has shown that hearing impairment is associated with increased cases of dementia, but how is visual impairment associated with cognitive function, if at all (Brody, 2021)?
A study published by JAMA Network Open in July 2021 examined the association between visual and cognitive function across a range of cognitive domains (language, memory, attention, executive function, and visuospatial ability) due to a lack of data on whether cognitive decline is specific to certain vision impairments or are associated with declines in certain cognitive domains (Varadaraj et al, 2021). The study analyzed data collected by the Baltimore Longitudinal Study of Aging between 2003 and 2019 from 1202 men and women ages 60 to 94 every 1 to 4 years, depending on the age group (Varadaraj et al, 2021). The researchers used three measures of visual function: visual acuity (the size that a pattern, such as letters on an eye chart, must be in order to be seen), contrast specificity (the contrast/brightness a pattern must be in order to be seen, and stereo acuity (depth perception) (Varadaraj et al., 2021). The study revealed that participants with low visual acuity scores had an increased risk of cognitive decline across the domains of language, memory, attention, and visuospatial ability (Varadaraj et al., 2021).
The 2021 JAMA Network Open study, however, may suggest a causal effect of cognitive function on visual impairment just as much as it does a causal effect of visual impairment on cognitive function. A study done published by JAMA Ophthalmology in September 2018 aimed to better understand the association and possible causal relationship between visual impairment and cognitive status (Zheng et al., 2018). The study, led by Diane Zhang of the University of Miami Miller School of Medicine, tracked the visual acuity (via Early Treatment Diabetic Retinopathy Study Charts) and cognitive abilities (via Mini-Mental State Examinations, or MMSEs) of 2520 adults ages 65 to 84 (Zheng et al., 2018). Baseline scores were taken between 1993 and 1995 in round 1 of the study, and subsequent score 2 years (round 2), 6 years (round 3), and 8 years (round 4) later (Zheng et al., 2018). The standardized effect size of the visual acuity scores on the MMSE scores was found to be greater than the reverse; the researchers found that visual impairment was twice as likely to affect cognitive function than vice versa (Zheng et al., 2018).
Visual impairment can have myriad downstream health effects due to lifestyle changes (e.g., exercising less, going out less, decreased social interactions), which can further affect cognitive function (Brody, 2021). For example, individuals with visual difficulties could overwork the brain, increasing the likelihood of experiencing language, memory, and attention deficits, among others, as one ages (Brody, 2021). As such, a good first step to maintain good vision and help combat cognitive decline is to schedule frequent eye exams (e.g., once every two years), especially as one enters late adulthood. With more frequent health checkups, one could identify and correct visual impairment as early as possible, lessening its potential downstream effects on cognitive function.
About the Author
Alison Chan is a freshman at Harvard College concentrating in Neuroscience with a secondary in Global Health and Health Policy.
References
Ackland, P., Resnikoff, S., & Bourne, R. (2017). World blindness and visual impairment: despite many successes, the problem is growing. Community eye health, 30(100), 71–73.
Brody, J. E. (2021). How Vision Loss Can Affect the Brain. The New York Times. Retrieved March 5, 2022, from https://www.nytimes.com/2021/09/06/well/live/vision-loss-brain-health.html
Varadaraj, V., Munoz, B., Deal, J. A., An, Y., Albert, M. S., Resnick, S. M., Ferrucci, L., & Swenor, B. K. (2021). Association of Vision Impairment With Cognitive Decline Across Multiple Domains in Older Adults. JAMA network open, 4(7), e2117416. https://doi-org.ezp-prod1.hul.harvard.edu/10.1001/jamanetworkopen.2021.17416
Zheng, D. D., Swenor, B. K., Christ, S. L., West, S. K., Lam, B. L., & Lee, D. J. (2018). Longitudinal Associations Between Visual Impairment and Cognitive Functioning: The Salisbury Eye Evaluation Study. JAMA ophthalmology, 136(9), 989–995. https://doi.org/10.1001/jamaophthalmol.2018.2493
A study published by JAMA Network Open in July 2021 examined the association between visual and cognitive function across a range of cognitive domains (language, memory, attention, executive function, and visuospatial ability) due to a lack of data on whether cognitive decline is specific to certain vision impairments or are associated with declines in certain cognitive domains (Varadaraj et al, 2021). The study analyzed data collected by the Baltimore Longitudinal Study of Aging between 2003 and 2019 from 1202 men and women ages 60 to 94 every 1 to 4 years, depending on the age group (Varadaraj et al, 2021). The researchers used three measures of visual function: visual acuity (the size that a pattern, such as letters on an eye chart, must be in order to be seen), contrast specificity (the contrast/brightness a pattern must be in order to be seen, and stereo acuity (depth perception) (Varadaraj et al., 2021). The study revealed that participants with low visual acuity scores had an increased risk of cognitive decline across the domains of language, memory, attention, and visuospatial ability (Varadaraj et al., 2021).
The 2021 JAMA Network Open study, however, may suggest a causal effect of cognitive function on visual impairment just as much as it does a causal effect of visual impairment on cognitive function. A study done published by JAMA Ophthalmology in September 2018 aimed to better understand the association and possible causal relationship between visual impairment and cognitive status (Zheng et al., 2018). The study, led by Diane Zhang of the University of Miami Miller School of Medicine, tracked the visual acuity (via Early Treatment Diabetic Retinopathy Study Charts) and cognitive abilities (via Mini-Mental State Examinations, or MMSEs) of 2520 adults ages 65 to 84 (Zheng et al., 2018). Baseline scores were taken between 1993 and 1995 in round 1 of the study, and subsequent score 2 years (round 2), 6 years (round 3), and 8 years (round 4) later (Zheng et al., 2018). The standardized effect size of the visual acuity scores on the MMSE scores was found to be greater than the reverse; the researchers found that visual impairment was twice as likely to affect cognitive function than vice versa (Zheng et al., 2018).
Visual impairment can have myriad downstream health effects due to lifestyle changes (e.g., exercising less, going out less, decreased social interactions), which can further affect cognitive function (Brody, 2021). For example, individuals with visual difficulties could overwork the brain, increasing the likelihood of experiencing language, memory, and attention deficits, among others, as one ages (Brody, 2021). As such, a good first step to maintain good vision and help combat cognitive decline is to schedule frequent eye exams (e.g., once every two years), especially as one enters late adulthood. With more frequent health checkups, one could identify and correct visual impairment as early as possible, lessening its potential downstream effects on cognitive function.
About the Author
Alison Chan is a freshman at Harvard College concentrating in Neuroscience with a secondary in Global Health and Health Policy.
References
Ackland, P., Resnikoff, S., & Bourne, R. (2017). World blindness and visual impairment: despite many successes, the problem is growing. Community eye health, 30(100), 71–73.
Brody, J. E. (2021). How Vision Loss Can Affect the Brain. The New York Times. Retrieved March 5, 2022, from https://www.nytimes.com/2021/09/06/well/live/vision-loss-brain-health.html
Varadaraj, V., Munoz, B., Deal, J. A., An, Y., Albert, M. S., Resnick, S. M., Ferrucci, L., & Swenor, B. K. (2021). Association of Vision Impairment With Cognitive Decline Across Multiple Domains in Older Adults. JAMA network open, 4(7), e2117416. https://doi-org.ezp-prod1.hul.harvard.edu/10.1001/jamanetworkopen.2021.17416
Zheng, D. D., Swenor, B. K., Christ, S. L., West, S. K., Lam, B. L., & Lee, D. J. (2018). Longitudinal Associations Between Visual Impairment and Cognitive Functioning: The Salisbury Eye Evaluation Study. JAMA ophthalmology, 136(9), 989–995. https://doi.org/10.1001/jamaophthalmol.2018.2493