It is well known about the positive association between the level of intelligence and income. But how do you feel about the causality?
Generally speaking, highly intellect persons are likely to gain more money. In contrast, people with intellectual disability are difficult to keep adequate income for satisfactory life. Therefore, financial aids for people with disabilities are necessary. It is a principle of the modern welfare-oriented states.
On the other hand, there is a hypothesis that low income does damage your brain activity. In a recent study, people with high socioeconomic status had more segregated brain structure. This result remained after the status in their childhood and other potential confounding factors were adjusted.
The Atlantic: How Income Affects the Brain
Since I have not read the manuscript thoroughly, I cannot evaluate the validity of the conclusion. But, it is possible that longitudinal exposure to financial difficulty causes irreversible damage to the brain. There is a hypothesis that chronic inflammation in the brain leads to depression, and poverty is one of the triggers of the onset of depression. As well, oxidative stress is suspected as a dominant cause of dementia. To sum up, some factors such as oxidative stress, inflammation, or depression as a clinical symptom mediate the link between poverty and chronic cognitive dysfunction.
Accepting this trajectory indicated above, what should we do? Improved social security is crucial for preventing people from further suffering. But it is not easy to deliver adequate wealth to everyone. "Free rider" issue should be discussed when giving money to many people equally. To begin with, proof of the causality between poverty and impaired cognitive function is not enough because there are no interventional studies.