Difficulty concentrating, making oneself understood, mood swings… Many symptoms can lead to the diagnosis of dementia, a term which “covers several diseases that affect memory, thinking and the ability to carry out daily tasks”, as explained by the World Health Organization (WHO). Worldwide, the UN organization estimates that 55 million people suffer from it and that it is one of the main causes of loss of autonomy. Still incurable, the question of early diagnosis is essential to delay the development of the disease.
Researchers from Loughborough University and Cambridge, England, questioned the existence of reliable markers capable of predicting the onset of dementia. They found that a decline in visual processing speed was associated with a higher risk of developing dementia. Their results are published in the journal Scientific Reports.
Loss of visual sensitivity could be an indicator of dementia
To arrive at these results, the researchers based themselves on data from the EPIC-Norfolk study, bringing together 8,623 volunteers. In this study, participants’ visual processing speed was assessed by the Visual Sensitivity Test (VST). Participants had to react based on the appearance of a light. They had to either press the “space” key or, depending on the instructions, press a specific key. The aim was to calculate visual processing speed, and identify the risk of future dementia. To do this, the researchers monitored the health status of the participants and calculated the risk of dementia using a statistical tool.
The researchers found that participants who performed worse on this test were more likely to develop dementia in the future. More specifically, the researchers note that “Reduced speed of complex visual processing is significantly associated with a high likelihood of a future dementia diagnosis.” According to the researchers, this loss of visual sensitivity would make it possible to detect dementia up to 12 years before diagnosis.
Alzheimer’s disease: areas of the brain linked to sight could be impacted
This is not the first time that researchers have looked at vision to help diagnose dementia. “Previous observational studies have also reported an association between visual impairment and increased risk of future dementia”, write the researchers. The latter specify to The Conversation that “toxic amyloid plaques associated with Alzheimer’s disease may first affect areas of the brain associated with vision, with parts of the brain associated with memory deteriorating as the disease progresses.
However, the researchers acknowledge limitations to their study, including that some people with disabilities may have refused to participate in the study. Also, the researchers note that it “Whether this test is sensitive to dementia treatments, including lifestyle changes, in multi-ethnic cohorts remains to be determined.”
Sources:
- Visual processing speed and its association with future dementia development in a population-based prospective cohort: EPIC-Norfolk – Scientific Reports.
- How your vision can predict dementia 12 years before it is diagnosed – new study – The Conversation
- Dementia – World Health Organization (WHO)