Children exposed to maternal depression throughout their first year of life are more likely than nonexposed children to develop mental disorders by age 6 years, particularly if their oxytocin system functioning is disordered, according to findings from a longitudinal study of 155 mother-child pairs.

Of the children in the study who were exposed to depression throughout their first year, 60% exhibited mental disorders by age 6 years, compared with only 15% of those born to mothers with no depression or other mental disorders, Ruth Feldman, Ph.D., reported at the annual meeting of the American College of Neuropsychopharmacology.

Anxiety disorders and conduct disorders were the most common conditions exhibited by the exposed children, although depression is likely to show more prominently at the next assessment when the children are aged 9 or 10 years, noted Dr. Feldman of Bar-llan University in Ramat Gan, Israel.

The exposed children also demonstrated lower social engagement with their mothers, lower playfulness and creativity, and diminished social involvement, compared with non-exposed children, and also were less verbal and expressed less empathy to the pain, suffering, and embarrassment of strangers, she said at a press briefing held in conjunction with the meeting.

Like their mothers, who had an increased likelihood of having disordered oxytocin functioning and who produced less peripheral oxytocin in their saliva, the children were found to have disordered functioning of the oxytocin system and lower salivary oxytocin levels.

The depressed mothers, as well as their children, had a threefold greater prevalence of a risky variant (a variant with two "G" alleles) of the oxytocin receptor gene.

Of note, the 40% of exposed children who did not develop a mental disorder by age 6 years demonstrated more normal functioning of the oxytocin system, and they had better social engagements and higher levels of empathy, Dr. Feldman said.

Furthermore, these children were born to women who had less disruption of the oxytocin system and a less risky variant (the "A" allele variant) of the oxytocin receptor gene, as well as typical levels of oxytocin in their saliva.

These women, despite their depression, had better emotional skills and an improved capacity for providing adequate care, Dr. Feldman said.

It appears that a properly functioning oxytocin system offers protection against the effects of chronic maternal depression in some children, she added.

Study participants were recruited from a larger sample of nearly 2,000 mothers who participated in a mental health survey when they delivered, and again at 6 and 9 months after delivery. The oxytocin measures and in-home observations between parents and children were conducted in those who participated in this portion of the study. In addition to the 20% of participants who had depression throughout the first postpartum year, 4% were diagnosed with subclinical depression and 4% with subclinical anxiety, and 62% had no signs of mental disorders or symptoms during the first year.

The findings are of interest because the oxytocin system is an open system with cross-generation effects, Dr. Feldman said, explaining that if the system is known to be disrupted – in cases of postpartum depression, for example – oxytocin-related interventions could be provided. Mothers could be instructed to increase maternal touch and gaze, or intranasal oxytocin could be administered, for example.