Age-Related Ophthalmic Conditions Associated with Increased Risk of Dementia Independently and Concurrently with Systemic Conditions

Article: Eye conditions linked to heightened risk of dementia
Source: British Medical Journal newsroom (U.K.)
Published: September 13, 2021

It is thought that reduced stimulation of the visual sensory pathways can accelerate cognitive decline, and a few small studies have suggested a link between ophthalmic conditions such as age-related macular degeneration, cataract, diabetes-related eye disease and glaucoma with cognitive impairment. Other studies have noted that systemic risk factors, such as as diabetes, high blood pressure, heart disease, depression and stroke also increase in incidence with increasing age. Researchers sought to investigate whether these ophthalmic conditions are associated with a higher incidence of dementia independently of these systematic conditions. They analysed data on 12,364 adults aged 55-73 years from the UK Biobank study; these individuals were initially assessed between 2006 and 2010 at baseline and followed up until early 2021. In the 1,263,513 data points collected, 2,304 cases of dementia were recorded. The data showed that age-related macular degeneration, cataract and diabetes-related eye disease, but not glaucoma, were independently associated with increased risk of dementia from any cause. In particular, compared with people who did not have ophthalmic conditions at the start of the study, the risk of dementia was 26% higher in those with age-related macular degeneration, 11% higher in those with cataract, and 61% higher in those with diabetes-related eye disease. They add that while glaucoma was not associated with increased risk of Alzheimer’s disease, it was associated with a higher risk of vascular dementia. Having both an ophthalmic condition and a system condition increased the risk of dementia further compared to having only an ophthalmic condition, with the greatest risk being concurrent diabetes-related eye disease and a systemic condition. Newly developed hypertension, diabetes, stroke, heart disease and depression mediated the association between cataract/diabetes-related eye disease and dementia. Finally, having more ophthalmic conditions showed a larger relative risk for dementia. The authors caution that this is an observational study based on self-reported and inpatient record data. Nonetheless, they conclude, "AMD, cataract and DRED but not glaucoma are associated with an increased risk of dementia. Individuals with both ophthalmic and systemic conditions are at higher risk of dementia compared with those with an ophthalmic or systemic condition only."

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Shang X, Zhu Z, Huang Y, et al. "Associations of ophthalmic and systemic conditions with incident dementia in the UK Biobank."British Journal of Ophthalmology.  13 September 2021. http://dx.doi.org/10.1136/bjophthalmol-2021-319508