A team of University of Wisconsin-Madison researchers found that chronic, toxic stress like poverty, neglect and physical abuse can have lasting negative impacts in children.
These kinds of stressors, experienced in early life, might be changing the parts of developing children's brains responsible for learning, memory and the processing of stress and emotion, researchers said.
These changes may be tied to negative impacts on behaviour, health, employment and even the choice of romantic partners later in life, they said.
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.
Researchers conducted extensive interviews with the children and their caregivers, documenting behavioural 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 outlined by hand each child's hippocampus and amygdala and calculated their volumes. Both structures are very small, especially in children, and researchers said the automated software measurements from other studies may be prone to error.
Indeed, their hand measurements found that 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. Putting the same images through automated software showed no effects.
Behavioural problems and increased cumulative life stress were also linked to smaller hippocampus and amygdala volumes.
The study was published in the journal Biological Psychiatry.