Exposure to poverty in early childhood was associated with smaller brain structures later in life, but nurturing seemed to offset poverty's negative effect, researchers found.

MRI scans showed that impoverished children had smaller white (P=0.005) and gray (P<0.001) matter volumes compared with normative values in early adolescence, according to Joan Luby, MD, of the Washington University School of Medicine in St. Louis, and colleagues.

Poverty was also a significant predictor of left hippocampus volume (P=0.02), and left amygdala volume (P=0.01), they reported online Oct. 28 in JAMA Pediatrics.

The association of poverty with volumes of the right hippocampus and right amygdala only approached statistical significance (P=0.09 for both).

However, supportive parental language during a laboratory task conducted while children were preschool age positively influenced left and right hippocampus volumes later in life (P<0.05 for both).

In addition, stress in a child's life negatively influenced brain development, but only the volume of the right hippocampus (P<0.05).

Regarding the influence of parental education on brain development, researchers found no effect.

"This work adds to our growing awareness that early adversity can powerfully influence human development throughout a life span," wrote Charles A. Nelson, PhD, of Boston Children's Hospital, in an accompanying editorial.

"Exposure to early life adversity should be considered no less toxic than exposure to lead, alcohol, or cocaine, and, as such, it merits similar attention from public health authorities," Nelson concluded.

There is evidence that children exposed to poverty have poorer cognitive skills, but neurobiological data in humans is sparse, Luby and colleagues said.

They investigated the effect of poverty on brain development in a group of children, ages 6 to 12, who were followed since preschool. The 145 children were recruited from a larger group of children who participated in a preschool depression study.

Parents were evaluated annually regarding stress during preschool years. After age 9, both children and parents were interviewed.

The assessment of supportive or hostile parenting was made after evaluating parent/child interactions during a task.

"The finding that the effects of poverty on hippocampal development are mediated through care-giving and stressful life events further underscores the importance of high-quality early childhood care-giving, a task that can be achieved through parenting education and support, as well as through preschool programs that provide high-quality supplementary care-giving and safe haven to vulnerable young children," the authors concluded.

The authors noted limitations of the study including an oversampling of children with depression in the original cohort, the absence of earlier imaging that would have allowed bidirectional mediation modeling, and the absence of more detailed aspects of poverty such as nutrition, parental psychopathology, and genetic factors.