In How Poverty Taxes the Brain researchers have found out in one particular study how much poverty affects the brain:
In a series of experiments run by researchers at Princeton, Harvard, and the University of Warwick, low-income people who were primed to think about financial problems performed poorly on a series of cognition tests, saddled with a mental load that was the equivalent of losing an entire night’s sleep. Put another way, the condition of poverty imposed a mental burden akin to losing 13 IQ points, or comparable to the cognitive difference that’s been observed between chronic alcoholics and normal adults.
It’s been discussed that standardized testing is just a way to show the socioeconomic status of school districts. As shown in these experiments, the cognitive ability of people under poverty is limited due to the processing of the hardships that go along with poverty. It’s not that the poor were of lower intelligence and that’s why they are in poverty, but that becoming poor means their brains have to put forth effort that it didn’t do before.