A new study has demonstrated, once again, that being poor is stressful, and that chronic stress is poison for the brain. Here’s the paper:
The income-achievement gap is a formidable societal problem, but little is known about either neurocognitive or biological mechanisms that might account for income-related deficits in academic achievement. We show that childhood poverty is inversely related to working memory in young adults. Furthermore, this prospective relationship is mediated by elevated chronic stress during childhood.
The scientists measured stress by looking at the “allostatic load” of the subjects when age 9 and 13, which is based on variables like blood pressure and levels of stress hormone, such as cortisol and norepinephrine. When the children were 17, they were given a simple test that measures working memory, which in this case meant temporarily remembering a sequence of random digits. (Working memory is strongly correlated with g.) The scientists uncovered a statistically significant link: the longer children had been poor, the worse their working memory. Furthermore, levels of chronic stress seemed to be the causal factor.
This paper builds on a large body of research linking stress during bran development to a wide variety of brain deficits, from reduced neurogenesis to problems with attention. Elizabeth Gould, who I’ve written about before, has done some quite powerful work on the subject:
Subsequent experiments [by Gould] have teased out a host of other ways stress can damage the developing brain. For example, if a pregnant rhesus monkey is forced to endure stressful conditions–like being startled by a blaring horn for 10 minutes a day–her children are born with reduced neurogenesis, even if they never actually experience stress once born. This pre-natal trauma, just like trauma endured in infancy, has life-long implications. The offspring of monkeys stressed during pregnancy have smaller hippocampi, suffer from elevated levels of glucocorticoids and display all the classical symptoms of anxiety. Being low in a dominance hierarchy also suppresses neurogenesis. So does living in a bare environment. As a general rule of thumb, a rough life–especially a rough start to life–strongly correlates with lower levels of fresh cells.
“Poverty is stress,” Gould says, with more than a little passion in her voice. “One thing that always strikes me is that when you ask Americans why the poor are poor, they always say it’s because they don’t work hard enough, or don’t want to do better. They act like poverty is a character issue.”
Gould’s work implies that the symptoms of poverty are not simply states of mind; they actually warp the mind. Because neurons are designed to reflect their circumstances, not to rise above them, the monotonous stress of living in a slum literally limits the brain.