New study reveals environment's role in post-natal depression

Posted on 19 May 2011

New research involving the University of York explores the interplay between genes and environment when determining whether a mother is at high or low risk for post-natal depression.

As part of the continuing Fragile Families and Child Wellbeing Study, launched in 1997, researchers, including Professor John Hobcraft, of York’s Department of Social Policy and Social Work and academics from Princeton, Penn State and Columbia Universities in the USA, examined the DNA of more than 1,200 mothers.

Our findings on the interplay between genetic markers and socioeconomic disadvantage regarding post-natal maternal depression break new ground

Professor John Hobcraft

The authors examined two genetic markers– 5-HTTLPR and Stin2 –that have been linked to risk of depression. These data were then examined against whether or not the mother was depressed in the first year of her child’s life and her level of education – with low levels of education being a proxy for a negative environment and higher levels for a positive one. 

The research is published in Proceedings of the National Academy of Sciences (PNAS).

While post-natal depression affected less than a quarter (17 per cent) of those sampled, the rates varied depending on whether the mother carried specific variants of a gene associated with biological sensitivity to her environment  and her level of education. 

  • Not surprisingly, mothers with genetic markers that made them more sensitive to their environment were more likely than other new mothers to become depressed if they were in a negative environment (ie low level of education).
  • Mothers without these markers looked the same across the education spectrum, with rates of depression the same regardless of environment. For these mothers, environment did not seem to have much of an impact.
  • However, when a mother with the ‘sensitive’ markers was in a positive environment (ie high level of education) she was actually less likely to become depressed than all other mothers, including those without the environmentally sensitive genetic markers.
  • Thus, the term “depression gene” is not quite right. In fact, the genetic markers previously linked with depression are actually signaling a more environmentally sensitive genetic makeup. This results in mothers with the sensitive genetic make-up actually being better off than other mothers in a positive environment, but worse off than others in harsher environments. 

Professor Hobcraft said: "Our findings on the interplay between genetic markers and socioeconomic disadvantage regarding post-natal maternal depression break new ground. Of key importance is the evidence that mothers with a particular combination of genetic markers do not seem to be all that affected by environmental disadvantage, but those with a different combination on the same gene are both less susceptible to maternal depression when advantaged but even more at risk of maternal depression when disadvantaged." 

Lead author, Colter Mitchell, of the Center for Research on Child Wellbeing and Office of Population Research, Princeton University, said: “The specific findings of this study are very interesting. But the paper is important because of the bigger concept it demonstrates. That is, certain genes may have a positive or negative effect depending on a person’s environment.”

Notes to editors:

  • The paper "The Role of Mother's Genes and Environment in Postpartum Depression," is published in Proceedings of the National Academy of Sciences.
  • It  was a collaborative effort by Colter Mitchell, Center for Research on Child Wellbeing and Office of Population Research, Princeton University; Daniel Notterman, Princeton University and College of Medicine, Pennsylvania State University; Jeanne Brooks-Gunn, Teachers College and the College of Physicians and Surgeons, Columbia University; John Hobcraft, Department of Social Policy and Social Work, University of York;  Irwin Garfinkel, School of Social Work, Columbia University; Kate Jaeger, Center for Research on Child Wellbeing and Office of Population Research, Princeton University; Iulia Kotenko, Department of Molecular Biology, Princeton University; and Sara McLanahan, Center for Research on Child Wellbeing and Office of Population Research, Princeton University.
  • More about the University of York’s Department of Social Policy and Social Work at www.york.ac.uk/spsw/.

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