Early life stress may leave lasting impacts on the brain, according to a recent study.

Researchers from the University of Wisconsin-Madison found that chronic, toxic stress like poverty, neglect and physical abuse might be changing the parts of developing children's brains responsible for learning, memory and the processing of stress and emotion. These changes may be tied to negative impacts on behavior, health, employment and even the choice of romantic partners later in life.

Early life stress has been tied before to depression, anxiety, heart disease, cancer, and a lack of educational and employment success, Pollak said.

"We haven't really understood why things that happen when you're 2, 3, 4 years old stay with you and have a lasting impact," Seth Pollak, co-leader of the study and professor of psychology, said in a statement. "Given how costly these early stressful experiences are for society ... unless we understand what part of the brain is affected, we won't be able to tailor something to do about it."

For the study, researchers recruited 128 children around age 12 who had experienced either physical abuse, neglect early in life or came from low socioeconomic status households.

They conducted extensive interviews with the children and their caregivers documenting behavioral problems and their cumulative life stress. They also took images of the children's brains, focusing on the hippocampus and amygdala, which are involved in emotion and stress processing. They were compared to similar children from middle-class households who had not been maltreated.

Researchers then outlined by hand each child's hippocampus and amygdala and calculated their volumes.

Based on the findings, children who experienced any of the three types of early life stress had smaller amygdalas than children who had not. Children from low socioeconomic status households and children who had been physically abused also had smaller hippocampal volumes.

Behavioral problems and increased cumulative life stress were also linked to smaller hippocampus and amygdala volumes.

Jamie Hanson, lead author of the study, said it is unknown why early life stress may lead to smaller brain structures. But he added that a smaller hippocampus is a demonstrated risk factor for negative outcomes.

"For me, it's an important reminder that as a society we need to attend to the types of experiences children are having," Pollak said. "We are shaping the people these individuals will become."

The findings were recently published in the journal Biological Psychiatry.