I think the more accurate statement would be poverty limits or even prevents access to meaningful education...
This impacts health literacy and the possibility of upward mobility...
Regarding health specifically, when one individual in a population suffers from a chronic illness/condition, an individual's personal accountability may be questioned...
When that chronic illness/condition becomes highly prevalent in that population, then you must examine the environment in which the population lives instead of simply concluding that population is dumb or doesn't care, regardless of their economic status...

The research mentioned in the article is still only measuring correlation, so the claim that "poverty is making people dumber" is unfortunately not founded on a causal link (due to no actual manipulation of any variables, outside of simply taking tests at different bill amounts). Since causation wasn't tested, there is no way to conclude whether poverty caused a reduction in intelligence, lack of intelligence caused poverty, or some other variable not mentioned.

It's obvious that socioeconomic status and intelligence are correlated, but there are many potential variables at work here.

And the study is challenging that.  That can be said to be true, but what the study was going for is that poverty also makes people dumber.

We aren't though.  Literacy, College and Highschool graduation are at all time highes.

The US is dropping in international rankings, but that has more to do with the ascendence of those countries... in particular eastern europeon and eastern asian countries that put an emphasis on education to the point of where  it negativly effects people socially.

For example in a lot of countries, school is where you go to have fun or sleep, because the real learning happens in after our study centers, that are often against the law.

People living in poverty tend to live near poor performing schools, many also have an unhealthy diet resulting in fatigue, and, therefore, low motivation.

During busy periods, I tend to eat fruit and yoghurt for breakfast. It makes me feel wired, and ready for anything. Eating a cooked breakfast, or cereals, in the morning tends to make me groggy and feel sick. It's a sidestep from this thread, but I'm guessing more "poor people!" eat cereal or bacon and eggs, versus the wealthy who are far more likely to have fruit salad or smoothie*

*Based on absolutely nothing other than gut feeling. Seems about right, though

it is not being poor that makes us dumber but the downward slope of poverty which keep us away from growth