Maternal depression in childhood and aggression in young adulthood: evidence for mediation by offspring amygdala-hippocampal volume ratio.

BACKGROUND There is abundant evidence that offspring of depressed mothers are at increased risk for persistent behavior problems related to emotion regulation, but the mechanisms by which offspring incur this risk are not entirely clear. Early adverse caregiving experiences have been associated with structural alterations in the amygdala and hippocampus, which parallel findings of cortical regions altered in adults with behavior problems related to emotion regulation. This study examined whether exposure to maternal depression during childhood might predict increased aggression and/or depression in early adulthood, and whether offspring amygdala:hippocampal volume ratio might mediate this relationship. METHODS Participants were 258 mothers and sons at socioeconomic risk for behavior problems. Sons' trajectories of exposure to maternal depression were generated from eight reports collected prospectively from offspring ages 18 months to 10 years. Offspring brain structure, aggression, and depression were assessed at age 20 (n = 170). RESULTS Persistent, moderately high trajectories of maternal depression during childhood predicted increased aggression in adult offspring. In contrast, stable and very elevated trajectories of maternal depression during childhood predicted depression in adult offspring. Increased amygdala: hippocampal volume ratios at age 20 were significantly associated with concurrently increased aggression, but not depression, in adult offspring. Offspring amygdala: hippocampal volume ratio mediated the relationship found between trajectories of moderately elevated maternal depression during childhood and aggression in adult offspring. CONCLUSIONS Alterations in the relative size of brain structures implicated in emotion regulation may be one mechanism by which offspring of depressed mothers incur increased risk for the development of aggression.