People with dementia often experience visual problems, which range in severity from difficulty seeing contrasts or colors to impaired understanding of spatial relationships. These visual problems typically manifest early in dementia, indicating that early vision testing may help identify those at risk. A recent study found that visual problems may predict dementia nearly 10 years before diagnosis.

The study involved more than 8,600 participants in a large, population-based prospective cohort. At the beginning of the study, participants took two visual sensitivity tests (simple and complex), which assess how quickly a person can process visual information and react to it. Researchers tracked the participants' cognitive and physical health for about 15 years.

They found that vision problems predicted participants' dementia risk an average of 9.6 years before a clinical diagnosis. A low score on the simple visual sensitivity test was associated with a 39 percent greater risk of developing dementia, and a low score on the complex test was associated with a 56 percent greater risk. These risks persisted even after accounting for the participants' ages. Interestingly, the vision testing was more sensitive to variables commonly associated with dementia risk (such as age, gender, and education) than traditional dementia assessments.

These findings suggest that visual problems predict future dementia risk. They also bolster previous research demonstrating that horizontal eye movements, such as those used when reading or viewing television, improve memory. Other lifestyle factors, including sleep, influence dementia risk, too. Learn more in this video featuring Dr. Rhonda Patrick.