The width of blood vessels in the retina may indicate brain health years before the onset of dementia other deficits, according to new research.

Psychological scientist Idan Shalev questions whether intelligence might serve as a marker indicating the health of the brain, and specifically the health of the system of blood vessels that provides oxygen and nutrients to the brain. Shalev and colleagues used digital retinal imaging to scan the small blood vessels of the retina.

Retinal blood vessels share similar size, structure, and function with blood vessels in the brain and can provide a way of examining brain health in living humans. Having wider retinal venules was linked with lower IQ scores at age 38, even after the researchers accounted for various health, lifestyle, and environmental risk factors that might have played a role.

Individuals who had wider retinal venules showed evidence of general cognitive deficits, with lower scores on numerous measures of neurospsychological functioning, including verbal comprehension, perceptual reasoning, working memory, and executive function.

The findings suggest that the processes linking vascular health and cognitive functioning begin much earlier than previously assumed, years before the onset of dementia and other age-related declines in brain functioning.

"Digital retinal imaging is a tool that is being used today mainly by eye doctors to study diseases of the eye," Shalev notes. "But our initial findings indicate that it may be a useful investigative tool for psychological scientists who want to study the link between intelligence and health across the lifespan."