I wonder, though, if they don't directly play off eachother, could they be affected by the same hormones? There's some research that shows that there's a relationship between BPD or Bipolar Disorder and estrogen, which plays a key role in Endometriosis. Without knowing what the research says, I would still easily say that my BD and BPD both show themselves much more during my hormone spikes that are caused or made worse by Endometriosis. A few other women with Endo and MI have also said the same thing.