Brain synchronization changes after high-fat diets

Researchers at Karolinska Institutet in Sweden have studied the impact of eating a high-fat diet, which may lead to obesity and diabetes. The results show a correlation between brain wave activity and brain functioning. The results are published in Nature Neuroscience.

It is already a well recognised that insufficient food intake during pregnancy may play an important role in pregnancy-related adverse effects. Consuming too much fat during pregnancy is one of the consequences of the high fat diet (in particular fat) consumed by pregnant women. It may therefore prove beneficial to both mother and unborn child to avoid the harmful effects of a high-fat diet while still allowing for brain development. There is a possibility that this could also have an impact for cognitive development due to high mobile cognitive abilities.

For the present study, researchers at Karolinska Institutet wanted to explore if and how brain wave activity was affected by eating a high-fat diet in pregnant women or on the way to term delivery. They also wanted to find out whether the high-fat diet affected the way the brain processes sensory information and therefore the ability to interact with others. To do so, they analysed EEG data of over a thousand pregnant pregnant women (twice as many as the equivalent of one year)—nursing mothers and non-pregnant mothers.

The participants were given three separate high-fat diets while being monitored by a rheumatologist who ensured they ate no more than two meals daily to monitor how a mother’s blood glucose levels fluctuate over a long period of time. The diet consisted of four lines of high fat foods, for example chocolate, saffron, maltodextrin and cornmeal.

The exposure to the high fat diet was not random but instead linked to the individual’s own meal history, as well as lifestyle and personal habits. The study participants, who were raised in ethically vegan and vegetarian households, participated in a psychological assessment three times: once at a planned delivery, once at term (usually around four months after) and once at term alone (usually six months after). In the first assessment, participants were asked to identify the high-fat diet they had consumed, the diet they were most or least likely to eat, the vowel sounds of one or two words (e. g. chocolate, sheep), and the colour of the sky—green, blue, red and yellow. The third examination, which was conducted two hours after birth, was of the same persons and evaluated a range of well-known cognitive skills: memory and attention.

The study participants were given a choice of keeping the high-fat diet, keeping a healthy weight and sticking to a lifelong life style in which they eat no more than two meals daily. Finally, exercise was offered as a condition reminder.

Participants registered basic brain wave activity during these three assessments, which was monitored by electrodes placed on the scalp. In particular, brain wave activity was present when they were responding to either the blood glucose or vowel sounds, which were both registered by a sensor placed over the ear in brain areas called pre-central and pars rectal cortex. Brain waves were then modulated with frequency.

Brain wave activity had a long-lasting effect on the participants’ brain activity. This was particularly the case in the context of high-fat diets: participants either increased or decreased their intake of high-fat foods during the three-month period of the follow-up period, with a similar pattern in their third assessment. Moreover, participants’ neural responses were more similar to physiological stimuli when responding to high-fat foods and visual novel sounds.

“Our results show that androgens do not change brain activity and improve the ability to remember who you have eaten with how much. Furthermore, our results show that the brain does regulate the frequency of high-fat diet-induced mental stress, which prevents (or limits) the cognitive development of non-impaired individuals by reducing the brain growth of non-higher cognitive ability, ” says Markus Holm, assistant professor at the Department of Cognitive Sciences, Karolinska Institutet.