The study, conducted by researchers from the University of Georgia, used functional magnetic resonance imaging (fMRI) to establish the neural mechanisms these compounds act upon in order to bolster cognitive ability.
It reveals that the compounds, lutein and zeaxanthin, lowered the amount of oxygen carried in the blood to specific areas of the brain.
In other words individuals with higher levels of lutein and zeaxanthin didn't require as much brain activity to complete the task, enhancing neural efficiency.
Establishing a mechanism
"If you can show that in fact there's a real mechanism behind this, then you could potentially use these nutritional supplements or changes in diet, and you could easily intervene and potentially improve cognition in older adults," said L. Stephen Miller, a professor of psychology and co-author of the study.
The study enrolled 40 adults aged between 65 and 86 years old. They were asked to learn and recall pairs of unrelated words, whilst fMRI monitored brain activity during the task.
The team found that adults with lower levels of lutein and zeaxanthin were more dependent on different parts of the brain to achieve the task using more brain power in the process
In contrast, those with higher levels of the two compounds exhibited less brain activity to complete the task, demonstrating enhanced ‘neural efficiency.’
"It's in the interest of society to look at ways to buffer these decline processes to prolong functional independence in older adults," Lindbergh said. "Changing diets or adding supplements to increase lutein and zeaxanthin levels might be one strategy to help with that."
Source: Journal of the International Neuropsychological Society
Published online ahead of print, doi.org/10.1017/S1355617716000850
“Relationship of Lutein and Zeaxanthin Levels to Neurocognitive Functioning: An fMRI Study of Older Adults.”
Authors: Catherine Mewborn, Billy Hammond, Lisa Renzi-Hammond, Joanne Curran-Celentano