Decades of research has documented that children exposed to maternal depression are at risk for psychiatric disorders. Research has identified several factors that are likely to contribute to the translation of risk of children with depressed mothers, including dysfunctioning of the hypothalamic-pituitary-adrenocortical axis, parenting behavior, and infant cognitive skills. Knowledge about how these factors may develop is missing, and earlier studies have failed to distinguish mothers with depression only and those with comorbid disorder.
In order to investigate the onset and continuity of differential developmental pathways in children with depressed mothers, this study was conducted to investigate how maternal depression is related to trajectories of maternal parenting behavior and infant cognitive skills, and how maternal depression is related to the infants’ daytime cortisol over time. Whether maternal depression diagnosis predicted the mother–toddler relationship was also investigated.
Two groups of mother–infant dyads were recruited and included in a longitudinal study; one group consisted of nondepressed mothers and their infants (n=24) and a second group consisted of clinically depressed mothers and their infants (n=26). Nineteen of the depressed mothers were diagnosed with comorbid anxiety disorder. There was little diversity in background variables between the different groups of mothers and infants, and the mothers had overall a high level of education. The mother–infant dyads were assessed repeatedly when the infants were 6, 12 and 18 months old.
The results showed that maternal depression was negatively associated with cognitive skills during the follow-up. However, the girls in the depressed (including infants with depressed only and comorbid mothers) and the nondepressed group evinced an improvement in cognitive skills over the first 18 months of life, whereas the boys were more stable in cognitive skill development. This suggests that boys follow a developmental pathway that is probabilistically related to less optimal development in the context of maternal depression.
The results also showed differential developmental pathways related to comorbidity of depression disorder. The infants of depressed only mothers set off on a developmental pathway with lower quality of maternal care, but with ordinary daytime cortisol. Subsequently they switched to a path that was closer to the infants of nondepressed mothers with respect to the quality of maternal care. This shift in developmental pathway concurred with remittance in maternal depression symptoms.
A different developmental pathway was found for the infants with comorbid mothers. These infants started on a developmental path with lower quality of maternal care, combined with elevated daytime cortisol during the first year of life. Over the follow-up at 18 months of age the path had changed direction to a one with increased quality of maternal parenting, although still lower as compared to the nondepressed, and yet with no different daytime cortisol as compared to the infants with depressed only and nondepressed mothers. This increase in quality of maternal parenting occurred in the context of chronic maternal depression and in a period of child development previous studies of depressed mothers have found to be associated with reduction in quality of parenting. Finally, the results showed that the toddler-parent relationship was directly related to infants’ cognitive skills and the mothers parenting behavior over the infants first 18 month. The results from the present study could possibly be related to the fact that most of the depressed only and comorbid mothers and their infants were in some type of treatment at the time of the study.
To summarize; results show differential developmental pathways related to the children’s gender and comorbidity of depression disorder. The results underscore the need to distinguish mothers with depression only and those with comorbid depression and anxiety disorder.