First study author Deanna M. Barch, PhD, chair of the Department of Psychological & Brain Sciences in Arts & Sciences, and colleagues publish their findings in The American Journal of Psychiatry.
The study builds on previous research from the team published last year, which found that children raised in poverty have reduced gray and white matter volumes in the brain, compared with those raised in richer families.
Additionally, they found that such brain changes were linked to poorer academic achievement.
For this latest study, the team set out to investigate whether childhood poverty may also lead to brain changes that influence mood and risk of depression, given that children raised in poorer families tend to be at higher risk of psychiatric illness and have worse cognitive and educational outcomes.
Poorer preschool children at greater depression risk aged 9 or 10
To reach their findings, Barch - also the Gregory B. Couch professor of psychiatry at Washington's School of Medicine - and colleagues enrolled 105 preschool children aged 3-5.
The team calculated the poverty levels of the children using an income-to-needs ratio, which accounts for a family's size and yearly income. At present, the federal poverty level in the US is $24,250 a year for a family of four.
Between the ages of 7-12, the children underwent functional magnetic resonance imaging (fMRI), which allowed the researchers to analyze the brain connections in the hippocampus - the region important for learning, memory and stress regulation - and the amygdala - a region associated with stress and emotion.
Compared with preschoolers from higher-income families, those from lower-income families demonstrated weaker connections between the left hippocampus and the right superior frontal cortex, as well as weaker connections between the right amygdala and the right lingual gyrus.
The researchers found that these weakened brain connections among preschool children raised in poverty were associated with greater risk of clinical depression at the age of 9 or 10.
"In this study, we found that the way those structures connect with the rest of the brain changes in ways we would consider to be less helpful in regulating emotion and stress," explains Barch.
What is more, the team found that the poorer children were at preschool age, the more likely they were to have weaker brain connections and depression at school age.
Early intervention key for positive emotional development
While the team's earlier research found that it may be possible to overcome some changes in brain structure linked to poverty - by improving a child's home environment, for example - no such association was identified in this latest study.
Still, Barch stresses that this does not mean nothing can be done to encourage positive emotional development among children from poorer families:
Last month, Medical News Today reported on a study that found children from poorer families are almost three times more likely to be obese than those from richer families
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