Possible Cause of Postpartum Depression Identified

Researchers have discovered a potential cause for postpartum depression, at least in animal studies.

According to Istvan Mody and Jamie Maguire of the David Geffen School of Medicine at the University of California, Los Angeles, dysregulation of a class of proteins called GABA receptors on the surface of certain neurons in the brain may be a cause of postpartum depression or psychosis.

In addition to binding with GABA, the GABA receptor sites can also bind with molecules called neurosteroids, which were the molecules of interest in this particular study. Neurosteroids are produced from hormones like progesterone. When progesterone levels rise sharply during pregnancy, neurosteroid levels also rise.

In order to keep a constant level of GABA receptor-derived inhibition - which the investigators theorize is necessary - the number of receptors must stay in synch with the level of neurosteroids. In other words, as neurosteroid levels rise during pregnancy, fewer receptor sites are necessary to provide the same amount of inhibition. Where things go wrong is after the birth, when neurosteroid levels drop, but there is not a corresponding increase in the number of receptor sites.

These findings provide a model that scientists can work with as they attempt to better understand postpartum depression, which could speed up the process of finding a treatment for it, the authors note. It should be kept in mind, however, that this is an animal model and it cannot be determined if the same process is at work in human postpartum depression. The next step, say the authors, is determining the applicability of the model to humans.

The results were published in the July 31 issue of Neuron.