With an extra, say, $300 per month, what can a parent living in poverty get for their child? The first things that come to mind might be diapers or school supplies, but research shows that they might be able to provide them with a bigger brain as well.

In the past decade, studies indicating a link between poverty, stress, and brain development have emerged. The newest breakthrough paper was published on Monday by Kimberly Noble of Columbia University and Elizabeth Sowell of the Saban Research Institute of Children’s Hospital Los Angeles. Their study, which examined over 1,000 children, was the largest of its kind, and revealed that a child’s brain surface area is related to family income.

In other words, the lower a family’s income, the higher the likelihood their child will have a smaller brain surface area. And this correlation is strongest for children at the very bottom of the family income spectrum, meaning for every additional dollar of earned income for poor families, the greater the increase in children’s brain surface area, compared to the same dollar increase for rich families.

The research shows that the regions of the brain that are linked to income level are associated with language and executive function, which include important skills for academic achievement, such as planning, focusing, and short-term memory.

Researchers hypothesize that this link between income and brain structure could be attributed to a lack of material goods, such as proper nutrition and health care, as well as repeated exposure to stressful situations that children in poverty often face, a problem called “toxic stress” by scientists.

So what does this mean for public policy?

A common argument, whether stated explicitly or implied, is that poor people are poor because of their own individual shortcomings. While correlation does not equal causation, this study sets the stage for further research to finally put this misconception to rest. We already know that wealthy children have a plethora of resources and support that poor children lack. One more thing we can now add to the list is healthy brain development, which makes it harder for poor children to grow into healthy and wealthy adults.

If this is the case, then the most direct way to alleviate the problem would be to give parents a cash allowance, or a monthly stipend, for each child in their household. There is already substantial evidence that points to the greater social benefits of such allowances, such as reducing material hardship and improving educational achievement of children. Cash allowances are an effective benefit that is already in place in almost every other economically advanced country.

Following this line of reasoning, Noble and co-researchers have already started work on a new study, which could directly prove the positive effect of cash allowances on children’s brain structure. The experiment will give mothers varying amounts of cash allowances every month and track the cognitive development of their children, from age zero to three.

With one of the highest child poverty rates in the developed world, we should be looking to policy solutions that are backed by rigorous research. Cash allowances are not a cure-all, but they are an investment our children deserve.