Providing cash aid to families with low incomes supports improved brain activity in babies, a preliminary study published Monday (January 24) shows.

The trial –– named Baby's First Years –– began in 2018, seeking to answer the question: What happens to baby's brain development when low income families receive regular cash income?

The study is still ongoing, but has so far shown that infants whose families received an additional $4,000 in annual income were more likely to have brain activity associated with thinking and learning.

These findings come on the heels of the the Child Tax Credit –– which provided additional income for parents –– expiring in the US and after years of studies that show growing up in poverty has an impact on brain development.

This new study takes those findings a step further by showing a cause and effect of giving aid to families who need it.

"All of the past work has been correlational," Dr. Kimberly Noble, a Teachers College, Columbia University neuroscience and education professor who co-authored the study, told NBC News.

"We could say based on the past work that poverty is related to these differences, but we couldn't say poverty is causing these differences. From a scientific perspective, the only way to answer that question is through a randomized clinical trial."