Nutrition protects against the impact of stress on the brain in early life

November 14, 2016

Science Daily/Universiteit van Amsterdam (UVA)

Young mice that grow up in stressful circumstances go on to have fewer cognitive-impairments and memory problems as adults if they are given enriched breast milk, scientists report.

In both humans and other animals, severe stress in early childhood (human examples are abuse and neglect or war trauma) results in impaired brain development and health issues later in life. For example, people exposed to early-life stress have a higher risk of developing depression, anxiety disorders and other diseases such as obesity, and on average have a lower IQ and a less effective memory.

Long-term hospital stay

Previous research conducted by neuroscientists Eva Naninck, Paul Lucassen and Aniko Korosi revealed that stress during early development also permanently changes the brain in mice. This current study conducted by the same group demonstrates that supplementing the nutrition of the mother during this early period can mitigate the harmful consequences of this early-life stress later on. Korosi: 'The fact that nutrients can influence impaired brain development deriving from stress in early childhood is hopeful. It enables us to look in a targeted way for nutritional interventions for children who are growing up in stressful circumstances, for example babies that have to undergo long-term hospital stays.'

To induce stress in young mice, the researchers gave mother mice only a limited amount of material with which to build their nests. As a result, their care for their young changed, and they left the nest more often in order to look for nesting material. Mothers in the control group who had plenty of nesting material at their disposal, on the other hand, stayed in the nest with their young for much longer periods of time.

The researchers gave half of the stressed mother mice a dietary supplement containing various nutrients which the body is unable to produce on its own, such as vitamins B6, B9 (folic acid) and B12 and the functionally related aminoacid, methionine.

The researchers found an increased hormonal stress response and reduced methionine levels in the brains of those young mice whose mothers were stressed, but were not given the nutritional supplement. In addition, these mice had an impaired memory as adults; they were less able to remember locations and objects.

The young of stressed mothers that were given supplemented nutrition were more similar to conspecifics growing up under normal circumstances. They had higher methionine levels in the brain and a lower hormonal stress response when young, and as adults they performed better on several memory tasks than the early-stress exposed mice whose mothers did not receive a nutritional supplement.

Human breast milk

The researchers emphasise that this explorative study was unable to fully explain precisely how the stress system and metabolism work together in this early period and in brain development. It is unclear whether the impaired development is due to the fact that stress-exposed mothers produce less nutritious milk, or if the problem lies with absorption in the body or brain of the young mice, who may also experience stress as result of the mother's unpredictable behaviour. However, according to Naninck the results are still valuable: 'Scientists tend to view metabolism and stress as unrelated systems, but we have demonstrated that in fact they work together in early brain programming. We hope that our insights can contribute to new nutrition strategies to mitigate the lasting effects of a seriously disturbed childhood.'

Before this kind of nutritional intervention can be used in people, it first has to be established whether human mothers and babies under serious stress, experience similar disturbances to mice. Currently, the group's first step is to investigate whether the nutritional content of human breast milk also changes under stress.

https://www.sciencedaily.com/releases/2016/11/161114082239.htm

Nutrition has benefits for brain network organization

September 7, 2017

Science Daily/University of Illinois at Urbana-Champaign

Nutrition has been linked to cognitive performance, but researchers have not pinpointed what underlies the connection. A new study found that monounsaturated fatty acids -- a class of nutrients found in olive oils, nuts and avocados -- are linked to general intelligence, and that this relationship is driven by the correlation between MUFAs and the organization of the brain's attention network.

The study of 99 healthy older adults, recruited through Carle Foundation Hospital in Urbana, compared patterns of fatty acid nutrients found in blood samples, functional MRI data that measured the efficiency of brain networks, and results of a general intelligence test. The study was published in the journal NeuroImage.

"Our goal is to understand how nutrition might be used to support cognitive performance and to study the ways in which nutrition may influence the functional organization of the human brain," said study leader Aron Barbey, a professor of psychology. "This is important because if we want to develop nutritional interventions that are effective at enhancing cognitive performance, we need to understand the ways that these nutrients influence brain function."

"In this study, we examined the relationship between groups of fatty acids and brain networks that underlie general intelligence. In doing so, we sought to understand if brain network organization mediated the relationship between fatty acids and general intelligence," said Marta Zamroziewicz, a recent Ph.D. graduate of the neuroscience program at Illinois and lead author of the study.

Studies suggesting cognitive benefits of the Mediterranean diet, which is rich in MUFAs, inspired the researchers to focus on this group of fatty acids. They examined nutrients in participants' blood and found that the fatty acids clustered into two patterns: saturated fatty acids and MUFAs.

"Historically, the approach has been to focus on individual nutrients. But we know that dietary intake doesn't depend on any one specific nutrient; rather, it reflects broader dietary patterns," said Barbey, who also is affiliated with the Beckman Institute for Advanced Science and Technology at Illinois.

The researchers found that general intelligence was associated with the brain's dorsal attention network, which plays a central role in attention-demanding tasks and everyday problem solving. In particular, the researchers found that general intelligence was associated with how efficiently the dorsal attention network is functionally organized used a measure called small-world propensity, which describes how well the neural network is connected within locally clustered regions as well as across globally integrated systems.

In turn, they found that those with higher levels of MUFAs in their blood had greater small-world propensity in their dorsal attention network. Taken together with an observed correlation between higher levels of MUFAs and greater general intelligence, these findings suggest a pathway by which MUFAs affect cognition.

"Our findings provide novel evidence that MUFAs are related to a very specific brain network, the dorsal attentional network, and how optimal this network is functionally organized," Barbey said. "Our results suggest that if we want to understand the relationship between MUFAs and general intelligence, we need to take the dorsal attention network into account. It's part of the underlying mechanism that contributes to their relationship."

Barbey hopes these findings will guide further research into how nutrition affects cognition and intelligence. In particular, the next step is to run an interventional study over time to see whether long-term MUFA intake influences brain network organization and intelligence.

"Our ability to relate those beneficial cognitive effects to specific properties of brain networks is exciting," Barbey said. "This gives us evidence of the mechanisms by which nutrition affects intelligence and motivates promising new directions for future research in nutritional cognitive neuroscience."

https://www.sciencedaily.com/releases/2017/09/170907112408.htm