Is it possible to disrupt the process by which a mother can transmit risk for psychiatric disorders to her offspring? New research suggests one way in which this may be possible.

Risk factors encoded in the genes of both parents are part of the inheritance of every child and are established upon the union of egg and sperm at the very dawn of each life. These inherited factors aside, cross-generational transmission of risk can occur in other ways. Research over several decades indicates, for instance, that the mother’s physical and mental health during pregnancy and after childbirth can contribute to her child’s risk of developing psychiatric conditions.

There is specific evidence that within the first year after birth, children born to women who suffer from major depression during pregnancy or from postpartum major depression have a significantly greater risk of developing problems in parts of their brain that regulate the emotions. This, in turn, has been associated with their heightened risk for subsequently developing various psychiatric and other health problems.

A research team led by 2015 BBRF Young Investigator Ryan J. Van Lieshout, M.D., Ph.D., FRCPC, of McMaster University, Canada, has published results of a study that was the focus of his grant, investigating whether treatment of mothers with postpartum depression during the first postpartum year can improve emotion-regulation in their infants.

The results, appearing in the journal Depression and Anxiety, indicate that treating women diagnosed with postpartum depression with cognitive behavioral therapy (CBT) for 9 weeks can indeed improve infant emotion-regulatory capacity. The study’s first author was John Krzeczkowski, Ph.D.

The researchers enrolled 80 mother-child pairs in their study. Half of the mothers had been diagnosed with postpartum depression. These women agreed to receive 9 weeks of CBT. The other 40 new mothers, socio-demographically matched, were not depressed; they and their infants served as controls. (The two groups of infants were also matched, in terms of sex and age).

Both groups of mothers and their children were tested at the beginning of the time at which the depressed mothers began CBT and after those treatments ended 9 weeks later. At both assessments, infants of the 80 mothers were tested for biomarkers of emotion regulation using two technology-based methods—one, a form of brain wave recording, the other measuring variability in infant heart rate. Mothers and their partners also separately filled out questionnaires asking them to assess emotion-regulation in the infant.

At the time of the first assessment, infants of women with postpartum depression exhibited poorer emotion regulation compared to the healthy control infants. The second assessment, 9 weeks later, showed that infants of the mothers who had been treated with CBT had improved results in both the brain wave and heart rate-variability tests, and scored higher in questionnaires filled out by both their mothers and their mothers’ partners. The researchers describe the emotion-regulation capacity of the infants at that point as “no longer differing from the healthy control infants,” using the measures of the study.

The study didn’t follow up the mother-infant pairs over a longer period to determine if the emotion-regulation improvements in the infants was sustained over time. This will be a subject for future studies. The researchers said the improvements seen in the infants of CBT-treated mothers in biomarkers for emotion-regulatory capacity may reflect more effective regulation by prefrontal networks in the infant brain, or reductions in amygdala hyperactivity.

How might these changes in the infant brain have been related to maternal treatment for major depression? The researchers suggested that treated mothers may have been more responsive to their infants’ needs, and hence their behavior with respect to the child was “more predictable.” The infants, they said, thus may have made beneficial “adaptive changes in physiological and behavioral systems underlying emotion regulation.”

If replicated, the team said, the results suggest the benefit of treatment of depressed mothers within the first postnatal year to lower risk of psychiatric and other negative impacts in their infants.