Visual Processing Speed Linked to Future Dementia Risk, Large Study Finds

A recently published study in "Scientific Reports" from the EPIC-Norfolk cohort has provided compelling evidence regarding the relationship between cognitive tests, particularly those assessing visual processing speed, and the risk of developing dementia. The study employed data from over 8,600 participants to explore how visual processing speed can help predict future dementia, putting forward findings that could improve dementia risk screening processes.

The study, involving researchers Ahmet Begde, Thomas Wilcockson, Carol Brayne, and Eef Hogervorst, utilized the Visual Sensitivity Test (VST) to evaluate visual processing. Their analysis indicated that individuals with lower VST scores were at a higher likelihood of being diagnosed with dementia in later years. The simple and complex versions of the VST showed hazard ratios of 1.39 and 1.56, respectively, for future dementia risk.

For context, other commonly used cognitive tests, such as the Hopkins Verbal Learning Test (HVLT) and Short Form Extended Mental State Exam (SF-EMSE), had higher predictive values (HR 3.45 and HR 2.66 accordingly). However, the VST, particularly the complex variant, demonstrated greater sensitivity in detecting variables often linked to dementia risk, which suggests its potential utility when combined with other neuropsychological tests.

The EPIC-Norfolk prospective cohort assessed thousands of participants over several years, looking at a range of factors from education level to physical activity, and relating these to cognitive function and health outcomes. Follow-up data revealed that certain demographics and health indicators, such as less education, lower physical activity levels, and the presence of health issues like diabetes and visual problems, were commonly associated with dementia.

Despite these associations, the study acknowledges limitations such as healthy volunteer bias, the overrepresentation of a white ethnicity among participants, and a reliance on self-reported outcomes that may be less accurate. Future research should aim to include a broader, more diverse population and incorporate objective measures.

In conclusion, while the VSTs alone did not outperform established cognitive tests in predicting future dementia, they were nonetheless significantly linked to dementia risk factors. Implementing VST alongside other tests could enhance the identification of at-risk individuals and facilitate the development of strategies for early intervention.

The full study is available and can be accessed online at https://doi.org/10.1038/s41598-024-55637-x, presenting an in-depth analysis of the role visual processing speed could play in early dementia screening.

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