Does Lack of Income Take Away the Brain’s Horses?

Daniel Lende over at Neuroanthroplogy [h/t: Linta Varghese]:

I don’t mean the pretty horses people ride, but the hippocampus (or sea horse) circuits in your brain, which are crucial to memory. New research in PLoS One, Association between Income and the Hippocampus, demonstrates a link between lower socioeconomic status and lower hippocampal grey matter density.

In Wednesday’s round-up I linked to Philip Cohen’s post, Income gradient for children’s mental health. Here’s the opening graph so you can get a sense of the gravity of the situation. The percentage of children with serious mental or behavioral difficulties is shown as a percentage on the left. The drop-off as income rises is dramatic.

In 2008 we documented that poverty poisons the brain:

As the article explained, neuroscientists have found that “many children growing up in very poor families with low social status experience unhealthy levels of stress hormones, which impair their neural development.” The effect is to impair language development and memory — and hence the ability to escape poverty — for the rest of the child’s life. So now we have another, even more compelling reason to be ashamed about America’s record of failing to fight poverty.

And then in 2009, we focused on how it’s really the social side of things doing the poisoning:

Empirical research on the connection between poverty and intellectual development can cut both ways—leading some to write off poverty as biological destiny, and others to look deeper into missed opportunities to lift youth over economic barriers…

While I advocate for the role that brain processes can play in social theory, the sword cuts both ways. Referencing the brain as central mediator of poverty hides the truth, and distorts our understanding. To take a more extreme example to illustrate the same point, it’s like saying that slavery is both harmful to people and morally wrong because it impacts brains.

This new research brings us back to a focus on the brain. The article, whose lead author Jamie Hanson is a graduate student in psychology at Wisconsin-Madison, brings a broader focus than just stress, through cortisol, acting as poison to the developing brain.