Previous studies showed that younger people who score low on intelligence tests, such as IQ, tend to be at higher risk for poorer health and shorter lifespan.
In the current study, psychological scientists led by Dr Idan Shalev of Duke University wondered 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.
To investigate the potential link between intelligence and brain health, they borrowed a technology from a somewhat unexpected domain – ophthalmology.
The team used digital retinal imaging to gain a window onto vascular conditions in the brain by looking at 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.
The researchers examined data from participants taking part in the Dunedin Multidisciplinary Health and Development Study, a longitudinal investigation of health and behavior in over 1,000 people born in Dunedin, New Zealand.
The findings were intriguing: 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. Participants 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.