Postpartum depression is really a combo-pack of nature and nurture, rather than what we have thought of as solely a “chemical imbalance.” Part of the cause of PPD is likely your genes, and part of the cause is likely what type of trauma, stress or environmental changes you have experienced that has caused certain of your genes to be expressed differently.
You aren’t born with one set of genes that never change, believe it or not. We know this thanks to the science of epigenetics. Epigenetics is the study of chemical reactions that switch parts of your genome off and on at strategic times and locations and what causes those chemical reactions to occur. As explained in easy to understand terms by The Week, your “… genes aren’t a fixed, predetermined program simply passed from one generation to the next. Instead, genes can be turned on and off by experiences and environment.”
Johns Hopkins has released the results of a small study this morning that they say shows two particular gene alterations that highly predict PPD. As described in their news release, “Johns Hopkins researchers say they have discovered specific chemical alterations in two genes that, when present during pregnancy, reliably predict whether a woman will develop postpartum depression. The epigenetic modifications, which alter the way genes function without changing the underlying DNA sequence, can apparently be detected in the blood of pregnant women during any trimester, potentially providing a simple way to foretell depression in the weeks after giving birth, and an opportunity to intervene before symptoms become debilitating.”
The genes in question? TTC9B and HP1BP3, which appear to be highly reactive to changes in estrogen levels. The idea is that some of us have brains that may be much more reactive to changes in estrogen during pregnancies than others, which may be why some of us get postpartum depression while others don’t.
Lead study author Zachary Kaminsky, PhD, explains, “The researchers noticed that women who developed postpartum depression exhibited stronger epigenetic changes in those genes that are most responsive to estrogen, suggesting that these women are more sensitive to the hormone’s effects. Specifically, two genes were most highly correlated with the development of postpartum depression. TTC9B and HP1BP3 predicted with 85 percent certainty which women became ill.”
If a future blood test can identify those women who have a high risk for PPD, then we can do a lot to help prevent it or at least reduce its severity and length, by educating them and their families in advance and creating a safety net that could start immediate, effective treatment at the first sign of symptoms.
A larger study is needed — this one included only 51 pregnant women. Meantime, this research is very exciting.
This study is published in the May 21 issue of the journal Molecular Psychiatry.
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Katherine Stone
