Summary: People with higher levels of lutein, a nutrient commonly found in kale and eggs, were more cognitively on par with younger people than their peers with lower lutein levels, a new study reports.

Source: University of Illinois.

Spinach and kale are favorites of those looking to stay physically fit, but they also could keep consumers cognitively fit, according to a new study from University of Illinois researchers.

The study, which included 60 adults aged 25 to 45, found that middle-aged participants with higher levels of lutein – a nutrient found in green leafy vegetables such as spinach and kale, as well as avocados and eggs — had neural responses that were more on par with younger individuals than with their peers. The findings were published in the journal Frontiers in Aging Neuroscience.

“Now there’s an additional reason to eat nutrient-rich foods such as green leafy vegetables, eggs and avocados,” said Naiman Khan, a professor of kinesiology and community health at Illinois. “We know these foods are related to other health benefits, but these data indicate that there may be cognitive benefits as well.”

Most other studies have focused on older adults, after there has already been a period of decline. The Illinois researchers chose to focus on young to middle-aged adults to see whether there was a notable difference between those with higher and lower lutein levels.

“As people get older, they experience typical decline. However, research has shown that this process can start earlier than expected. You can even start to see some differences in the 30s,” said Anne Walk, a postdoctoral scholar and first author of the paper. “We want to understand how diet impacts cognition throughout the lifespan. If lutein can protect against decline, we should encourage people to consume lutein-rich foods at a point in their lives when it has maximum benefit.”

Lutein is a nutrient that the body can’t make on its own, so it must be acquired through diet. Lutein accumulates in brain tissues, but also accumulates in the eye, which allows researchers to measure levels without relying on invasive techniques.

The Illinois researchers measured lutein in the study participants’ eyes by having participants look into a scope and respond to a flickering light. Then, using electrodes on the scalp, the researchers measured neural activity in the brain while the participants performed a task that tested attention.

“The neuro-electrical signature of older participants with higher levels of lutein looked much more like their younger counterparts than their peers with less lutein,” Walk said. “Lutein appears to have some protective role, since the data suggest that those with more lutein were able to engage more cognitive resources to complete the task.”

Next, Khan’s group is running intervention trials, aiming to understand how increased dietary consumption of lutein may increase lutein in the eye, and how closely the levels relate to changes in cognitive performance.

“In this study we focused on attention, but we also would like to understand the effects of lutein on learning and memory. There’s a lot we are very curious about,” Khan said.

Funding: This work was supported by the department of kinesiology and community health at the University of Illinois and the Hass Avocado Board.

Source: Anne Walk – University of Illinois
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Full open access research for “The Role of Retinal Carotenoids and Age on Neuroelectric Indices of Attentional Control among Early to Middle-Aged Adults” by Anne M. Walk, Caitlyn G. Edwards, Nicholas W. Baumgartner, Morgan R. Chojnacki, Alicia R. Covello, Ginger E. Reeser, Billy R. Hammond, Lisa M. Renzi-Hammond and Naiman A. Khan in Frontiers in Aging Neuroscience. Published online June 9 2017 doi:10.3389/fnagi.2017.00183

Abstract

The Role of Retinal Carotenoids and Age on Neuroelectric Indices of Attentional Control among Early to Middle-Aged Adults

One apparent consequence of aging appears to be loss of some aspects of cognitive control. This loss is measurable as early as mid-adulthood. Since, like many aspects of cognition, there is wide variance among individuals, it is possible that behavior, such as one’s diet, could drive some of these differences.

For instance, past data on older humans and non-human primates have suggested that dietary carotenoids could slow cognitive decline.

In this study, we tested how early such protection might manifest by examining a sample (n = 60) of 25–45 year olds. Carotenoid status was assessed by directly measuring macular pigment optical density (MPOD) which has shown to be highly correlated with the primary carotenoid in brain, lutein.

Cognitive control was measured using event-related potentials during the performance of cognitive control tasks designed to tap into different aspects of attentional (i.e., selective attention, attentional inhibition, and response inhibition) control. Our results showed that, across participants, MPOD was related to both age and the P3 component of participants’ neuroelectric profile (P3 amplitude) for attentional, but not response, inhibition.

Although younger adults exhibited larger P3 amplitudes than their older adult counterparts, older subjects with higher MPOD levels displayed P3 indices similar to their younger adult counterparts in amplitude.

Furthermore, hierarchical regression analyses showed that age was no longer a significant predictor of P3 amplitude when MPOD was included as a predictor in the model, suggesting that MPOD may partially contribute to the relationship between age and P3 amplitude. In addition, age and MPOD were shown to have independent associations with intraindividual variability of attentional control, such that younger individuals and individuals with higher MPOD showed less intraindividual variability.

These results show a relationship between retinal carotenoids and neuroelectric indices underlying cognitive control. The protective role of carotenoids within the CNS may be evident during early and middle adulthood, decades prior to the onset of older age.

“The Role of Retinal Carotenoids and Age on Neuroelectric Indices of Attentional Control among Early to Middle-Aged Adults” by Anne M. Walk, Caitlyn G. Edwards, Nicholas W. Baumgartner, Morgan R. Chojnacki, Alicia R. Covello, Ginger E. Reeser, Billy R. Hammond, Lisa M. Renzi-Hammond and Naiman A. Khan in Frontiers in Aging Neuroscience. Published online June 9 2017 doi:10.3389/fnagi.2017.00183