CNN: Why Do Black Brains Differ from White Brains? Racism!
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From CNN:

MRIs show racism and poverty may alter brain development of Black children, study says
By Justin Gamble, CNN
Published 9:40 AM EST, Sat February 4, 2023

Black children living in poverty face increased instances of stress and trauma that can alter their brain development, a new study found.

The study was published this week by the American Journal of Psychiatry. Researchers at Harvard University examined MRI scans of 7,350 White and 1,786 Black children ages 9 and 10. The data in the study was collected by the National Institutes of Health in 2019.

This is data from the lavish Adolescent Brain Cognitive Development (ABCD) study of 10,000 or so kids age 9 to 10 that I wrote about in connection with Fuerst and O’Connor’s important study of the correlation between racial admixture and IQ.

Researchers found that increased stressors like economic hardship and systemic racism play a significant role for Black children and can lead to the development of mental health issues as they age, the study said.

The stressors contribute to Black children having less gray matter in their brains, a byproduct of absorbing “toxic stress.” The study defines the stressors as “prolonged exposure to adverse experiences” that lead to excessive stress hormones and “disrupt the immune and metabolic regulatory systems.”

I don’t find it at all implausible that, say, hearing gunfire in your neighborhood not infrequently as a child could be bad for your growing brain. But from scanning the article, I don’t see much reason to think it’s more plausible than that families with less functional brain structures tend to wind up in shootier neighborhoods. Or, quite likely, both could be true to some extent.

What you’d need to do is study children’s brains over a number of years and correlate changes to the stress they endured in the interim.

In the study, researchers found that Black children often developed behavioral problems later in life such as PTSD, anxiety and depression. These children also were susceptible to drug and alcohol abuse and suicide attempts and were likely to commit violence, the study said.

Nathaniel Harnett, an assistant professor of psychiatry at Harvard Medical School who led the study, told CNN their analysis sought to examine how early the effects of structural inequities and racism would appear in brain development. Harnett said his team began exploring a cognitive development study to dispel “this kind of folk belief that Black and White people have categorically different brains.” …

But they wound up finding from the ABCD that brains did differ by race, so then they announced that it was due to racism.

Harnett said his team’s analysis underscores the need for “large-scale structural and systemic change,” especially in policy.

If black children’s cognitive development is suffering from too much violence in their neighborhoods, then clearly what we need to do is depolice them so that black homicides go up dramatically after George Floyd. Because reasons.

Harnett said the data researchers examined suggested “that what’s really driving any differences are the sort of disproportionate burden of life experiences that people have.”

This is the 150-year-old question of nature vs. nurture, first outlined by Francis Galton. It’s a really tough problem, and you can’t just sort of Assume We Have a Can Opener your way to the right answer. For instance, the full study contains no text strings of “genes” or “genetic.”

Researchers said Black children are much more likely to be exposed to violence, live in disadvantaged neighborhoods, and combat systemic racism daily than White children.

Nor can you do good science by just assuming that all the problems of black people, especially ones born in this century, are the results of “systemic racism.”

… “The adversity that these kids are exposed to, it impacts everyone, but it disproportionately burdens Black children in this case,” he said.

If I recall correctly, ABCD will do brain scans of the participants every two years for a decade. (They also have gene scans for all the kids.) However, this study appears to be only using the first planned MRI, not the subsequent ones. You can see the usual problem with using just one scan to try to disentangle the effects of nature and nurture, genes and environment. They can use the future brain scans to compare against subsequent nurture, but those haven’t happened yet.

The authors seem to deal with these obvious, classic problems by simply ignoring their existence.

From the study:

An independent-samples t test demonstrated that racial groups differed in intracranial volume (t=19.44, df=8235, p<0.001).

In other words, whites average larger brains than blacks. But the researchers did not consider that as a possible reason for lower black educational achievement. It’s unthinkable.

Thus, the gray matter volume of our a priori regions of interest (PFC, hippocampus, amygdala, and insula) was normalized as a proportion of estimated intracranial volume ([region volume/intracranial volume]×100) and averaged across left and right hemispheres.

So they did analyses of the proportional differences in brain regions, but not of overall brain size: Occam’s Butterknife.

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