A novel study has indicated that a plethora of eye conditions may potentially increase the risk of developing dementia.
The research, published in the British Journal of Ophthalmology, has signified that a range of eye conditions, such as age-related macular degeneration, cataracts, and diabetes-related eye disease, increase an individual’s risk of dementia.
One of the principal signs of dementia is vision impairment, with reduced stimulation of visual sensory pathways understood to increase the progression of the neurodegenerative disease. Previously, minor investigations have indicated that there might be a correlation between these eye conditions and cognitive impairment, in addition to systematic conditions such as diabetes, high blood pressure, heart disease, depression and stroke, also being associated risk factors.
A closer look at eye conditions
To examine whether these eye conditions are linked with an increased risk of dementia independently of these systematic conditions, the team analysed data of 12,364 adults aged between 55 and 73 who were enrolled in the UK Biobank study. The participants were examined between 2006 and 2010 at baseline and followed up until 2021, with 2,304 new cases of dementia being recorded during this 1,263,513 person-years of follow-up.
The data illuminated that age-related macular degeneration, cataracts, and diabetes-related eye disease, but not glaucoma, were independently associated with increased risk of dementia from any cause. The risk was 26% higher in those with age-related macular degeneration, 11% higher in those with cataracts, and 61% higher in those with diabetes-related eye disease compared to those who did not have any eye conditions at the start of the study. Despite glaucoma not being associated with an increased risk of Alzheimer’s disease, it was discovered to cause an elevated risk of vascular dementia.
The impacts of systemic conditions
Participants of the study were asked if they had ever experienced a heart attack, angina, stroke, high blood pressure or diabetes, and were also assessed for depression. The team ascertained from this that diabetes, heart disease, stroke, and depression, were all linked with an increased risk of dementia.
Having any of these systemic conditions in combination with an eye condition further exacerbated the risk of dementia, with the greatest risk displayed in participants who had diabetes-related eye disease and a systemic condition. People with more eye conditions demonstrated a larger relative risk of dementia.
Limitations of the study
Due to being an observational study, the authors note several limitations that are predominantly related to data capture. They explained that the eye conditions were defined based on self-reported and inpatient record data, which potentially underestimated their prevalence. Furthermore, death and medical records may not have obtained all cases of dementia, with some of dementia recorded in the follow up possibly occurring before any eye diseases.
The authors commented: “Age-related macular degeneration, cataracts, and diabetes-related eye disease 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. Newly developed hypertension, diabetes, stroke, heart disease and depression mediated the association between cataract/diabetes-related eye disease and dementia.”