Post-Partum Depression: It Could Be Genetic
One finding from a broader study of programmed responsiveness to the environment
By Patricia Lamiell
New analysis of data on more than 1,200 mothers, conducted by TC faculty member Jeanne Brooks-Gunn and colleagues, found a “strong and significant” interaction between certain genetic markers and post-partum depression. The finding supports the broader hypothesis that people are genetically inclined to be “more or less reactive to the environment.”
The study was reported in “The Role of Mother’s Genes and Environment in Postpartum Depression,” a paper published on May 17 by the National Academy of Sciences. Brooks-Gunn and her colleagues found that people who have genetic markers affecting the release through the nervous system of serotonin, a natural chemical produced by the body, are likely to react more strongly to environmental factors.
“Individuals who carry the more reactive marker might respond to environmental conditions for better and for worse,” Brooks-Gunn said. “If the environment is less positive, then having that particular genetic marker is linked to doing worse – in this study, being more likely to have depression in the year after a baby's birth. And if the environment is positive, then having the genetic marker is linked to doing better -- in our case, being less likely to have depression in the year -- which is what we found.”
Scientists sometimes refer to the phenomenon as “different susceptibility,” or the “orchid and dandelion,” Brooks-Gunn added. Someone “with the reactive gene marker is an orchid [and] does really well in a good environment but not very well in a bad environment.” But “dandelions, who do not have the reactive gene marker, do about the same regardless of their environment,” she said.
New mothers with the reactive gene marker who had low levels of education were more likely to have depression, Brooks-Gunn said, while mothers with the same reactive gene marker but were highly educated were less likely to be depressed. Education had a stronger effect than socio-economic status (SES), although the two are linked, in that women with less education tend to have lower SES status.
Women of low socio-economic status (SES) are about twice as likely as high-SES women to have post partum depression. However, the study found that the risk of post-partum depression is greater for women in the most reactive groups, regardless of socioeconomic status. Women whose genetic makeup made them highly sensitive to the environment were more likely to become depressed in a low-socioeconomic environment than low SES-women who did not have the genetic marker for high sensitivity. Conversely, mothers with the genetic marker for high sensitivity were more likely to respond positively to high-status environments.
The team found support for the corollary as well: Less reactive women were less likely to be depressed in low SES environments, but also less likely to respond positively to the positive environment of high-SES status.
The researchers analyzed data on mothers from seven U.S. cities, drawn from the “Fragile Families and Child Wellbeing Study” (FFCWS), which was co-authored Brooks-Gunn.
Brooks-Gunn, the Virginia and Leonard Marx Professor of Child and Parent Development at TC, has conducted broad-based research on the effects of genetics and the environment on physical and mental health. She and her colleagues first reported the findings in February at the annual meeting of the American Association for the Advancement of Science.
The Fragile Families and Child Wellbeing Study (FFCWS), which provided the data for the current analysis, is based on a stratified, multi-stage, probability sample of children born in large U.S. cities between September 1998 and September 2000.
Brooks-Gunn’s co-researchers were: Colter Mitchell, Sara McLanahan and Kate Jaeger, Center for Research on Child Wellbeing and Office of Population Research, Princeton University; Daniel Notterman, Department of Molecular Biology, Princeton, and the College of Medicine, Pennsylvania State University, Hershey, Pennsylvania; Iulia Kotenko, Department of Molecular Biology, Princeton; John Hobcraft, University of York, United Kingdom; and Irwin Garfinkel, School of Social Work, Columbia University.