In the first study of this kind, an international team of Penn researchers and collaborators discovered that genetics and environmental factors contribute to how socioeconomic status contributes to the structure of the brain.
Your education, your work, your income, and the neighborhood in which you live are factors that are considered to represent socio-economic status (SES), achieving education and cognitive ability from physical and mental health. Contributes to various health and social outcomes.
The brain acts as an obvious mediator between SES and many of these consequences. However, the mechanism by which it does so remains ambiguous, and scientific studies have shown whether the effects of SES on the brain are encoded by our genes or caused by the environment in which we live. Could not show.
With a new report Science AdvancesAn international research team, led by scientists at the University of Pennsylvania and the Vrije Universite of Amsterdam, is moving forward to disperse the relative contributions of genes and the environment. Using the largest dataset ever applied to this question, the team contributed to the impact of SES in complex interactions with both genetic and environmental effects with effects that span different brain regions. I found proof that I would.
“What we saw in this study is that some of the relationships between the brain and socioeconomic states can be explained by genetics, but even after explaining genetics, there is still much more to do with that relationship. There is, “says Gideon Nerve, marketing officer. He is a professor at the Wharton School of the University of Pennsylvania and a co-author of the study. “This suggests that socio-economic conditions can somehow sneak into the skin and further negatively impact the social and economic disparities we see around us.”
This work is the result of a large academic collaboration co-led by Nave and Vrije’s Philipp Koellinger, a senior author of a study called BIG BEAR for brain imaging and genetics in action research. Martha Farah, a professor of psychology at the University of Pennsylvania and another co-author of this study, is a principal investigator in the study.
Mapping of SES footprint in the brain
A significant number of studies have shown that SES has characteristics in the brain.
“I’m studying the relationship between SES and the brain,” says Farrer. “And the question that always comes up is what is the cause of these differences? Are the features of SES encoded in the genome, or the experience of living at different levels of SES has these effects on the brain? Is it both? We could also show that genes and the environment appear to have different effects on different parts of the brain. “
Researchers used a large dataset, UK Biobank, to better understand these relative contributions. Previous studies used small sample sizes to study the link between the brain and SES, or the definition of SES was inconsistent. In contrast, UK Biobank covers a wide range of types of data collected by standardized methods, including brain scans, genomic sequencing, and SES measurements. As a result, the research team was able to search for patterns of SES factors and brain scan information in nearly 24,000 individuals.
Each person was assigned two SES “scores”. One is a combination of income, vocation and achievement of education, and the other is a combination of neighborhood and vocation. Looking at the two scores together, they accounted for about 1.6% of the variation in total brain volume. This is a previously seen discovery.
Researchers then dig deeper into the brain scan data to look for specific areas of the brain tracked by SES. They discovered numerous brain regions associated with SES, including some surprises. Notably, the cerebellum, which has not been analyzed in many previous studies, has shown a substantive relationship with SES. Located near the brainstem, the cerebellum is responsible for higher levels of function, including movement and balance, and cognition and learning.
“There is a correlation between SES and the amount of gray matter throughout the brain,” says Nave. “They are small, but the sample size of our study is large, so we can be confident that they are genuine.”
Hyeokmoon Kweon, lead author of the study and PhD student at the Free University of Amsterdam, adds: In fact, by aggregating these small brain-SES relationships, we can predict significant amounts of SES differences. “
Nature vs. nurturing
Tens of thousands of individuals at UK Biobank have also sequenced their genomes, allowing researchers to look for evidence of the genetic effects of SES on the brain. For this analysis, they created a single index of SES and gene linkage based on previous studies identifying single nucleotide polymorphisms (variations of one “letter” in the DNA code) that correlate with SES. Did.
Using this indicator, they found that genetics could explain more than half of the relationship between gray mass and SES in some areas. The prefrontal cortex and islands involved in abilities such as communication, decision making, and empathy have been found to be particularly strongly dominated by genetic influences. However, the relationship between SES and the gray mass of other brain regions (such as the cerebellum and temporal lobe) is less correlated with genetics and may instead affect the environment.
Emphasizing the potential impact of the environment, researchers looked at another variable in the data, the body mass index (BMI). Genetics plays a role in BMI, but BMI also arises from non-genetic factors such as nutrition and physical activity. Even after controlling the known genetic association between brain anatomy and SES, researchers have found that BMI can account for an average of 44% of the relationship between SES and gray mass. ..
This finding suggests that it may appear in the structure of the brain as well as environmental factors that may contribute to an increase in BMI, such as malnutrition and inadequate exercise.
Basis for intervention
Researchers suggest that their findings do not require anything to improve the effects of SES on the brain, but instead, thoughtful policymaking is associated with SES differences in health and society. He emphasizes the ability to deal with disparities.
“The issue of genetic or environmental contributions to SES differences is controversial, partly because of their perceived policy implications,” says Farrer. “Many people think that it is possible and necessary to change the environment if the difficulties of people with low SES are caused by the environment, but go to an illogical conclusion. Nothing needs to be done as long as they are genetic. Genetically caused problems can also be ameliorated by environmental intervention. For example, phenylketonuria, a serious congenital metabolic syndrome, PKU. , Or a dietary change for someone with glasses for common vision problems. “
According to researchers, policy interventions can be one solution, addressing environmental justice concerns associated with poor areas, for example. “Deterioration of air quality in areas with low SES can cause inflammation and other adverse effects on the brain,” says Nave. “As just one example, regulations that mitigate air pollution can eliminate the harm and improve health and well-being altogether, regardless of where you live. The same is true for free, quality kindergartens. You can. In this case, genetics is not fate. “
According to the team, more research is needed to move from correlating to identifying causes in terms of understanding the environmental impact of SES on the brain. “As more and more data is available, we expect to be able to generate such studies soon. It will help shape targeted interventions.”
reference: Kweon H, Aydogan G, Dagher A, and others The anatomy of the human brain reflects the separable genetic and environmental elements of socio-economic states. Science Advances.. 2022; 8 (20): eabm2923. doi: 10.1126 /sciadv.abm2923
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