Duke University researchers studying brain health have found a link between the width of blood vessels in the retina and intelligence quotient (IQ). Their findings could eventually have a significant impact on understanding dementia and other cognitive issues years before any deficits occur.
According to Medical News Today, the Duke researchers turned to the medical specialty of ophthalmology for a technique -- digital retinal imaging -- to examine the intelligence-brain health relationship. They published the results of their study in the journal Psychological Science.
Lead psychologist Idan Shalev and his colleagues initially wondered whether intelligence could be a marker for brain health, particularly the condition of the blood vessels that furnish nutrients and oxygen to the brain. Digital retinal imaging provided a look at small blood vessels at the back of the eye. This was important because these vessels resemble vessels in the brain as far as structure, size, and function.
Individuals receive an IQ score as the result of taking any of a number of tests. MedlinePlus states that average IQ scores are between 90 and 110. An individual who scores at least 165 can call himself a genius. A number less than 70 suggests intellectual disability.
The Duke team analyzed data from subjects in the Dunedin Multidisciplinary Health and Development Study, an ongoing project to track the health, development, and general well-being of young people in New Zealand. Its subjects numbered more than 1,000 and were born in the city of Dunedin between April 1, 1972 and March 31, 1973.
The scientists found that subjects with wider retinal venules -- vessels that connect capillaries to veins -- at age 38 showed lower IQ scores. This occurred even after they took into consideration potential influences related to health, environmental risk factors, and lifestyle.
These subjects also had signs of general cognitive deficits. They had lower scores in verbal comprehension, working memory, perceptual reasoning, and executive functioning. Researchers were surprised to discover that individuals who had wider venules when they were 38 also had lower IQs when they were 25 years younger.
In addition to showing a relationship between IQ and the width of certain blood vessels in the eye, the Duke findings suggest that whatever processes link the two occur much earlier in life than experts imagined, possibly years before patients develop dementia or other age-related cognitive declines.
The primary purpose of digital retinal imaging is to study eye diseases. The Duke team sees using this tool as a way to look at the potential relationships between IQ and health throughout a person's life. Another eventual purpose is using the imaging to develop better diagnoses and treatments for boosting oxygen levels in the brain and ward off cognitive decline associated with aging.
Vonda J. Sines has published thousands of print and online health and medical articles. She specializes in diseases and other conditions that affect the quality of life.
- blood vessels
- intelligence quotient
- Duke University