Few studies have looked at how feast or famine affects the developing brain without taking into account other things that can cause adversity. This is despite the fact that food insecurity is a growing problem in the United States, and the coronavirus pandemic has made it even worse.
A new study by neuroscientists at the University of California, Berkeley, recently re-created the effects of not having enough food on young mice and found changes in the adult brains of the mice that lasted for a long time.
Linda Wilbrecht, a psychology professor at UC Berkeley and a member of the Helen Wills Neuroscience Institute, said, “We show that irregular access to food in late childhood and early adolescence affects learning, decision-making, and dopamine neurons in adulthood.”
Cognitive flexibility—the capacity to come up with fresh ideas when the external environment changes—was one significant behavioral difference.
Mice that are looking for rewards may be rigid, sticking to one strategy even when it no longer works, or they may be adaptable, quickly trying out new ones. “We discovered that the consistency of the food supply mice had as young animals influenced how adaptable they were under various circumstances as adults.” She spoke.
Epidemiological studies have linked childhood and adolescent food insecurity to weight gain in later life, as well as to learning difficulties and lower math, reading, and vocabulary test scores. Other poverty-related problems, such as maternal depression and environmental stressors, however, are a confounding factor in these studies. The new study was made to look at the effects of food insecurity on development and behavior in a controlled setting that couldn’t be done with people.
The research has applications for people. With federally funded free or reduced-price breakfast and lunch programs available in schools across the United States, policymakers recognize the significance of a healthy diet from early childhood through high school. Additionally, the federal Supplemental Nutrition Assistance Program (SNAP) offers benefits to help struggling families with their food budgets. These food programs have been shown to have an impact on families living paycheck to paycheck, particularly in terms of improved academic performance and graduation rates.
However, there may be instances when children are unable to access food programs, such as over the summer. When benefits are disbursed over a long period of time, programs may unintentionally create a feast and famine cycle that prevents low-income families from being able to buy food at the end of each payment cycle. In 2021, 2.3 million households — or 6.2% of all households with children — were food insecure, according to a recent report from the U.S. Department of Agriculture.
In my opinion, we need to realize that even brief food insecurity has consequences because the brain doesn’t simply catch up later. “The way a person’s brain works can be negatively impacted by food insecurity over time,” said Wilbrecht. “We are observing how access to food affects the development of critical skills like learning and decision-making during childhood and adolescence. In this country, we can address the issue of food access. Existing feeding and benefit programs can be improved by ensuring more dependable and consistent access to benefits or food. Supporting food programs is a good idea because it supports brain development.
The study, carried out in collaboration with professors Helen Bateup and Stephan Lammel of UC Berkeley, and their lab associates, will be published in a future print issue of the journal Current Biology. On July 20, it was published online.
adaptability to rules that change
In order to mimic human food insecurity in mice, Wilbrecht and her coworkers, including Robert Wood Johnson Foundation Health and Society Scholar Ezequiel Galarce, delivered food on an erratic schedule while still allowing enough food to maintain a healthy body weight. This diet plan started a week before mice reached puberty, which is the equivalent of late childhood in humans, and continued for 20 days until mice reached the age of late adolescence. A second group of mice were given access to food whenever they desired.
Then, using foraging tasks in which mice searched a shifting environment for rewards, they examined adult cognition. For instance, a behavior—in this case, discovering which scent produced the Honey Nut Cheerios—might be effective for a limited period of time, but not always. The location of the reward was now predicted by a second odor.
When tested as adults in both certain and uncertain environments, the cognitive flexibility of the mice with adequate food and those with insufficient food was evidently different. Food-insecure mice were better at adapting to uncertain situations than well-fed mice. On the other hand, well-fed mice were better at adapting to situations where they knew what to expect.
She said that to determine how these various flexibility profiles affect survival, “you would have to test in the field.” The authors write: “We identify both gains and losses of function in learning and decision-making that are wrought by experience of scarcity, which makes the findings nuanced but hopeful.”
Food insecurity had a big effect on the brains of male mice, but not on the brains of female mice
When Wilbrecht and his team have been modeling adversity, “this is one of the most robust behavioral effects we’ve ever seen,” they said.
However, food insecurity had other distinctly detrimental effects on female mice. When given unlimited access to food as adults, the females who experienced food insecurity as children tended to gain weight, which is a trait shared by adults who experienced food insecurity. Male mice didn’t exhibit this effect.
The reward network in the brain, which is controlled by the neurotransmitter dopamine, was also examined by doctoral student Wan Chen Lin and researchers from the Bateup and Lammel labs, and they discovered changes there as well in male mice.
According to Wilbrecht, dopamine system neurons, which are important for decision-making, learning, and reward-related behaviors like addiction, were found to have undergone significant input and output changes. It means that the parts of the brain that help us learn and make decisions have changed more.
For instance, the dopamine neurons that project to the nucleus accumbens underwent changes in their synapses, and the dorsal striatum also underwent changes in its dopamine release. Several other studies have shown how important these dopamine neurons are for learning and making decisions.
The researchers are continuing their studies on these mice in order to ascertain whether adult food-insecure mice are more prone to addictive behaviors that are connected to the dopamine network.
Former postdoctoral fellow Polina Kosillo, former doctoral candidate Christine Liu, and senior scientist Lung-Hao Tai are additional UC Berkeley authors on the paper. The work was funded by the Robert Wood Johnson Foundation and the National Institutes of Health (R21 AA025172, U19NS113201). Bateup works as a researcher for both the Weill Neurohub and the Chan Zuckerberg Biohub.
