It’s rather clear that social-economic factors have a huge part to play in the development of an individual, but when discussing this we typically refer to education, something that can be more or less manipulated at any time, albeit with various degrees of difficulty. How do social-economic aspects affect the brain, though? Martha Farah, the founding director for Penn’s Center for Neuroscience and Society is currently conducting research in this direction, and so far her preliminary results seem to suggest that the  brain’s response to circumstances of social class should not be taken lightly. For instance, there seems to be direct link between poverty and stunting of brain development in children.

Through out her career, Farah has mainly specialized in neuroscience fields related to vision and memory, however she has always been intrigued by how social class affects brain development. As the developed world is facing an ever discrepant segregation of classes, the topic is worthy of consideration.

“I actually became pretty obsessed with social class, this major dimension of variation in the human race and certainly in American society,” Farah said.

“We’re so segregated by class, we don’t even realize we’re segregated because we don’t even know what life is like just two miles north of here,” she said.

The stress of poverty on the brain

This image, compiled using data from multiple researchers, shows how cortical thickness varies across species. In humans, on the right, there are noticeable changes as a person ages.

As sociological studies have corroborated, it seemed to Farah that child-rearing and children’s early experience was very different depending on social class.

Poor children don’t get as much exposure to language as their wealthier counterparts, research has found, and they tend to get more negative feedback. What they do hear is not as grammatically complex, with a narrower range of vocabulary. There is less understanding of how children develop and what they need for cognitive development, Farah said.

Stress seems to also play a major role. Parents of low-income are more predisposed to subject their children to a stressful environment, since they themselves are stressed at their own term by the uncertainties of meeting means, bad neighborhoods, crowding and so on. Stressed parents are less patient and affectionate, further stressing their children, according to Farah.

A recent study published in the journal PLoS One seems to be very revealing in this respect, involving a group African American adolescents who came from households of low socioeconomic status. When the participants were age 4, their parents’ responsivity (warmth and supportiveness) was evaluated, then some 11 to 14 years later, the now adolescents were subjects to a stress test. The participants had to hold a talk in front of a unfriendly audience.

After the test was over, the participants had their saliva sampled to measure cortisol – the stress hormone. Researchers found that cortisol reactivity was related to parental responsivity, and the less parental responsivity, the less of a normal stress response the volunteers had.

“You might say, ‘Well, of course life is more stressful in lower socioeconomic strata,’ ” she said. “But the degree of magnitude of the stress that they live with is just unbelievable.”

The idea that stress impairs brain development is thus born, but an even bigger question is beckoned – would this damage be permanent? It is unknown whether that stunting can be reversed, but you shouldn’t assume that it’s unchangeable, Farah said.

“If you’re interested in child policy and stuff, the important bottom line is: You never want to say, ‘Oh, damaged goods, so there’s nothing we can do now,’ ” she said.

The study

Along with Brian Avants, assistant professor of radiology, Farah followed 53 children who came from low socioeconomic status from birth through adolescence and performed brain imaging. The researchers performed their evaluation with two scales in mind: environmental stimulation (“child has toys that teach color” at age 4, and “child has access to at least 10 appropriate books” at age 8 etc) and parental stimulation (parent holds child close 10-15 minutes per day” at age 4).

The researchers wanted to see whether they could predict the thickness of cortisone based on these two major social factors. Greater cortical thickness in childhood is associated with poor outcomes such as autism, Avants explained. Later in adolescence, relatively reduced cortical thickness is linked to higher IQ and other mental processes.

From this study, Farah and colleagues suggested that environmental stimulation at age 4 predicts cortical thickness in the late teenage years, but parental nurturing did not appear to be linked.

Their work has yet to be published, and the final conclusions will be very interesting to follow when the time comes. Farah and colleagues call for awareness, in the meantime. There are far fewer children with autism than there are poor children in the United States, for example, but autism as a condition gets more attention from the science community than the neurological implications of poverty, the authors write.

Farah presented the study at the Society for Neuroscience meeting in November.

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