Are poor people actually biologically dumber than the rich? Do MRI scans of brains suggest that poor children (many of them minorities) lack the gray matter for long-term memory, complex learning, and the moderation of emotional behavior?

It's not that hard to  to imagine the reaction if a conservative think tank published a "scientific" study along these lines.

But what about a progressive think tank at UW-Madison? Would it be all right then?

The latest issue of the La Follete Policy Report, published by the Robert M. La Follette School of Public affairs at UW-Madison, features an article titled "Using Brain Scans to Understand Links between Economic Status and Cognition."

Its author is Barbara (Bobbi) Wolfe, a professor of public affairs, economics, and population health sciences, and a former director of the La Follette School, who relies on MRI scans to analyze the differences in the brains of poor kids. 

Her basic thesis: poverty causes kids brains to shrink, making them dumber. She doesn’t actually use the word 'dumb," but the message is pretty hard to miss.

She puts it this way: "We view the brain as a bridge between biology and the environments in which poor, middle-income, and rich children grow up; we hypothesize that a child’s environment affects brain development."

In a rare moment of caution, Wolfe notes that: "just because a relationship is observed consistently across time and countries does not mean the link is causal or that we understand the nature of the tie."
But she then proceeds to draw all manner of links:

After processing neuroimaging data from each subject we conducted a random effects regression analysis that controlled for the wave of the MRI scan, the total volume of the brain, the child’s age, the child’s sex, and interactions between age and sex. We did this for all of our regions of interest of the brainincluding the hippocampus, prefrontal cortex subregions, the occipital lobe, and the cerebellum. We estimate the influence of socioeconomic status on specific regions of the brain. Our baseline measure of socioeconomic status is tied to household income. We average income levels for each child and divide the children into three groups: low income (families with income below $35,000), middle income (families with incomes between $35,001 and $100,000), and high income (families with incomes over $100,000).

What does Wolfe say they found? Let’s start with the hippocampus, which is associated with "long-term memory functioning… learning, control of neuroendocrine functions, and moderation of emotional behavior." It turns out the poor are short-changed.

Our analysis finds evidence of a significant association between the size of the hippocampus and family income.  These results clearly suggest that for children in higher income  families the hippocampus is larger than among those in lower  income families. The findings suggest a deprivation difference; that is, a child in a low-income family has a hippocampus that makes up smaller part of her/his brain compared to middle and higher income children. This difference in the hippocampus, perhaps due to stress tied to growing up in poverty, might partially explain differences in long-term memory functioning and, in particular, differences in learning, control of neuroendocrine functions, and moderation of emotional behavior.

It’s pretty much the same story with the the prefrontal cortex which is "considered to be central to attention, inhibition, emotion regulation, complex learning, and mental processing." Here again the poor come up short. 

Wolfe writes that "children from poor families have smaller proportions of their brains allocated to the dorsolateral prefrontal cortex than do children from middle or higher income families."

Again we find evidence of statistically significant differences in the proportion of the brain allocated to gray matter in one component of this critical region of the brain, the dorsolateral prefrontal cortex, which is crucial in attention, working memory, and cognitive control processes.
What does this mean?

Wolfe says the results suggest that "we expect that children in low-income families may be more likely to exhibit impairments in planning, goal attainment, and problem-solving ability."

If that’s too esoteric, Wolfe goes on to argue that these "alterations in the brain region" may "slow down translation of visual stimulation into mental images and lower cognitive ability more generally."

This is not exactly brain surgery, but again, the author is not exactly a brain scientist either. The article identifies Wolfe as "a professor of public affairs, economics, and population health sciences." In other words she is not a doctor. She bases the article on "work with College of Letters and Sciences Distinguished Professor of Psychology Seth Pollak, psychology Ph.D. candidate Jamie Hanson, economics Ph.D. candidate Nicole Hair, and others at UW-Madison."
But is this real science? For starters: why does she correlate brain size only with income? Do children without intact families have smaller hippocampuses? What about diet? Parenting styles?

Would brain changes correlate with the age of the birth mother? Drug use? Alcoholism? What about birth-weight?  Race? Wolfe's study has nothing to say on those questions.

She admits that this poor-have-different brains science is "new work." 

But the political and ideological agenda is obvious. If you accept her thesis that income = brain size, then we have a whole new set of excuses for educational failure and for treating the poor as a "victim class." Maybe we aren’t so equal after all. Maybe equality of opportunity is a myth. You can’t expect these kids to learn if they have smaller brains, right? 

Wolfe will argue that she is on the side of the angels, because she insist that the differences are caused by the environment, not by genes, and that she is making the case for interventions to solve the evils of poverty. 

But this is a double-edged sword, because, as Wolfe notes, we can’t always be sure which is the chicken and which is the egg. While she is firmly in the poverty-causes-dumbness camp, couldn’t the data also be used to argue that dumbness-causes-poverty? Correlation is not causation; and as Charles Murray and others have found, arguments about biological and genetic differences in intelligence are fraught with controversy. 

But then again, they weren't liberal academics from UW-Madison.