Children from poor families perform worse than their peers in many school tests, and then their overall academic performance and social performance are not as good as their peers.
Studies in sociology and neuroscience show that a bad growing environment will adversely affect the size, shape and function of children's brains, putting them at a disadvantage in future education and work.
The potential impact of poverty on brain development makes people start to think whether this damage can be reversed by simple intervention. At present, a study in preparation hopes to explore whether moderate economic subsidies can make poor children's brains healthier.
1. The harm of poverty
Poverty may adversely affect the size, shape and function of children's brains. Although the specific mechanism of poverty affecting brain development has yet to be discovered, researchers have been trying to reduce this effect through a direct means-granting subsidies to poor families. For the 6,543.8+billion children and adolescents living in poverty all over the world, poverty deprives them of more than basic material needs. From composing symphonies to solving calculus equations, human wisdom comes from the "three-pound miracle" of the brain. However, scientific research has found that poverty is likely to hinder the normal development of the brain. In IQ, reading and other tests, children from poor families generally perform worse than their peers. For them, it is more difficult to graduate from high school, go to college and get a degree. As adults, they get lower wages and are more likely to lose their jobs. These associations are not surprising, and the level of brain development is only one of many factors that lead to these consequences. So, what kind of influence will poverty have on brain development? Until the last decade, our views on this were still vague.
My laboratory, together with several other laboratories, began to explore the social-economic status of families. Status, SES)-a measure index covering income, education level and professional reputation-and the relationship between children's brain health. We found that the differences in the size, shape and actual function of children's brains are related to SES.
Recognizing the potential harm of poverty to brain development, we want to find a simple and feasible way to reduce the harm caused by poverty. To this end, we plan to study the influence of family economic pressure on children's brain health by granting subsidies. This is the first study to explore whether a moderate increase in income contributes to brain development. If we get a positive conclusion, it will clearly point out a road from basic brain science to public policy.
When I started this research 15 years ago, I was only a graduate student at the University of Pennsylvania. My mentor Martha Farah (Martha? Farah wants to know how poverty affects early brain development. Fortunately, I became the first student to challenge this question.
Our project needs to choose research methods carefully. The most attractive technology at that time was brain imaging, which took pictures of the brain through powerful machines, thus revealing the structure and function of the brain. The effect of brain imaging technology is exciting, but it is also extremely expensive: a single scan usually costs hundreds of dollars, which does not include the remuneration paid to the subjects and research assistants who analyze the data.
2. Correlation of household income
We decided to find a simpler and cheaper way to recruit as many subjects as possible. Finally, we decided to use standardized methods to measure cognitive ability. Unlike previous studies, we no longer rely on a wide range of achievement indicators, such as high school graduation rate, because there is no region in the brain responsible for high school graduation. Many different brain circuits are responsible for various cognitive skills, many of which are very important for academic and life achievements. For example, if someone's Wernicke area in the left hemisphere of the brain is damaged, they will have difficulty in understanding language. At the same time, neuroimaging research also points out that healthy people use the same brain area when listening to others. Scientists infer that when healthy individuals perform a task that requires listening and understanding language, they will use Wernicke's area.
We decided to use mature psychological tests instead of brain scans to evaluate children's language ability. The question we want to study is: What is the relationship between SES gap and brain function?
We recruited several groups of children from different socio-economic backgrounds as the research objects, and their ages ranged from preschool to adolescence. In the experiment, they accepted a series of cognitive tests to test the integrity of the circuit structure of various parts of the brain. We have drawn highly consistent conclusions from many experiments. Generally speaking, children from poor family backgrounds often perform poorly in tests of language, memory, self-control and concentration.
On the other hand, for us and other teams engaged in similar research, more advanced brain imaging technology is really needed to verify whether family SES affects the shape and size of children's core brain regions participating in advanced cognitive processes. Four independent research groups recently reported that children with higher parents' income tend to have a larger hippocampus (a structure deep in the brain, responsible for memory coding). Other studies mainly focus on the influence of poverty on the shape and size of the cerebral cortex (the outer folded layer composed of brain cells responsible for cognitive processing). Among them, some early studies have tested whether there is a correlation between SES and cerebral cortex volume.
Care must be taken when measuring cortical volume. Because a large cortical surface area multiplied by a small cortical thickness, or a large cortical thickness multiplied by a small cortical surface area, it is possible to get the same cortical volume, so researchers are easily misled. Cortical thickness decreases with age; At the same time, the surface area of cortex increases with age, just as we started to have a small can of tomato sauce, and then its bottom area gradually increased, and finally it became as big as a soup can.
Recently, we used a set of measurement software to test whether SES gap will affect both the surface area and thickness of cerebral cortex. This is the largest study on this issue so far. We analyzed the brain structure of children and adolescents with different SES in America 1099. We found that parents' education level and family income are related to the surface area of children's cerebral cortex. The surface area of children's cerebral cortex with annual family income below $25,000 is 6% smaller than that of children with annual family income above $654.38+$5,000. This correlation exists widely in many areas of the brain, especially those responsible for language processing, impulse suppression and other self-regulation. Previous studies have repeatedly confirmed that these abilities are affected by SES.
3. Individual differences that cannot be ignored
We considered several key variables. First, we considered the genetic background of each subject. Data analysis shows that the influence of SES differences on brain structure has nothing to do with racial factors. In addition, we also found huge individual differences. For example, the surface area of the cerebral cortex of children and adolescents in some poor families is larger, while the surface area of the cerebral cortex of children with superior family conditions is smaller. Although children from higher income families often have larger cortical surface area, our research team can't directly predict a child's cortical surface area based on family income.
The correlation between family income and cerebral cortex surface area is the most obvious in the lowest income group, but it tends to weaken in the higher family income group. In other words, in the poorest families, the difference in family income has a greater impact on the brain structure.
In another study, we discussed the relationship between SES differences and cortical thickness. Generally speaking, the thickness of cortex will decrease with age. However, our research shows that the social and economic status of families will have an impact on this trend. When family SES is low, the thickness of children's cerebral cortex has a sharp decline in the early stage, and the decline trend slows down after puberty. However, when SES is high, until the late adolescence, the trend of cortical thickness decreasing with age is more gentle.
This discovery shows that in some cases, adversity can accelerate the maturity of the brain and make the brain of young children grow faster. The thickness of the cerebral cortex of children from poor families drops rapidly, indicating that their brains lack "plasticity", which can change the brain structure to adapt to childhood and adolescence learning.
Of course, one of the most important questions we need to answer is whether the differences in brain structure will affect children's cognitive ability. We find that children with higher family income can concentrate more and suppress inappropriate reactions. The difference in brain structure (cortical volume or thickness) may explain why teenagers with low-income family background have lower academic performance than others 15%~44%. This kind of research has made remarkable achievements, but they are still in the primary stage. We need to continue to find out what causes the relationship between ses and brain development. Is it nutrition, neighbors, school quality, parenting style, family pressure, or a combination of these factors? Are these differences caused by acquired experience or heredity?
It is difficult for current research to directly answer these questions. However, some studies have shown that the life pressure brought by income gap and the different parenting styles will lead to the differences in children's brain structure. In low-income families, parents give their children less support, and children are more likely to be hostile, which will lead to negative results-in this study, the hippocampus is smaller. Our laboratory is investigating whether long-term stress and lack of language communication between parents and children can explain these findings to some extent.
4. Relevance is not equal to causality
There is a long-standing question: can the difficulties experienced by poor children in their early life be traced back to the embryonic period, or are they influenced by family income after birth? Recently, our team found that the brain function of babies within four days after birth has nothing to do with parents' income and education level, which also confirmed that SES affects the development of brain structure through acquired experience. However, this result still needs more research, because the sample we studied only contains 66 families. It is worth mentioning that some research teams have found that children's brain structure and function will be significantly different after one year of birth.
In short, at present, we don't have enough evidence to explain the relationship between family, social status and economic conditions and children's brain development. In the future research, clarifying the relationship between socio-economic status, early childhood experience and brain development will still be the priority direction. Although a large number of studies have provided evidence for the relationship between family income and brain development, a key problem remains unsolved. People often say that "correlation is not equal to causality", which explains this lingering uncertainty: Is the poor family environment leading to the low level of brain development, or is it because of the different growth process that some children are struggling in their studies or future work?
Neuroscience research has been silent on the issue of causality. In order to study causality, we need to apply the golden rule of scientific experiments: randomized controlled trials. Among them, the randomly assigned "treatment" group will receive some kind of intervention, while the same randomly assigned group will receive "control" measures, which enables us to judge the impact of this intervention on brain development.
In this kind of research, researchers need to find intervention measures that can effectively narrow the differences in socio-economic status. Many measures are effective, but these interventions often face great challenges: high-quality interventions are very expensive and difficult to implement on a larger scale. In addition, they tend to "gradually disappear"-when children no longer enjoy the services of this program, the positive impact of intervention will weaken over time.
In view of these difficulties, we decided to consider a simpler intervention. Our plan is to give cash subsidies to families to study whether this measure will affect children's brain development. Unlike other services such as counseling and child care, cash subsidies make it possible for parents to make the best financial decisions for themselves and their children. The idea of providing basic income security is gradually gaining recognition, and some charities and governments have started pilot projects.
But so far, no study has really measured the impact of income subsidies on children's brain development. We are raising funds for the first randomized controlled trial to test the causal relationship between poverty alleviation and brain development. Although the premise of this study is simple and clear, our goal is ambitious. At the beginning, we plan to recruit 65,438+0,000 low-income American mothers who happen to have children and give them a monthly subsidy of $333 or $20 at random. If mothers who have just given birth in the hospital agree to participate in the study, a sum of money will be charged to their debit cards. As the research continues, their debit cards will automatically transfer a sum of money every month. We have no restrictions on how to use the money. In the first three years after the child is born, we will follow up the family and then evaluate whether unconditional cash subsidy will affect the child's cognitive ability and brain development.
We will also carefully analyze all aspects of family life, including stress, the quality of family relationships and how parents use the money. Recently, a one-year preliminary study involving 30 low-income mothers shows that our method is highly feasible and debit cards can be a reliable means to provide subsidies to mothers.
We assume that the increase of family income will bring a series of positive effects to poor families. When children pass their infancy, they will have better development in vision, hearing and other key cognitive skills, which is equivalent to that of children from high-income families. If our hypothesis holds, then our experiment may affect the formulation of social policies, thus affecting the lives of millions of poor families with children. In our view, these policies can be implemented through a simple management system. Although income may not be the only factor that determines a child's development trajectory, it is the easiest to change from the perspective of policy implementation. At least, it can be used as a "down payment" to promote the healthy development of children's brains.