Jen,Picture PMS on steroids. Unmedicated, I literally cease to function in the week before my period. Instead of mood swings, I get full-blown depression, anxiety attacks, and panic attacks. Instead of crying easily, I cry constantly, and for up to two hours at a time without being able to stop. I call my mother and cry for hours at a time, and at all hours of the night (did I mention the insomnia) I want to quit school, curl up in a ball, go to sleep, and never wake up. This is on top of the physical symptoms, which include food cravings, IBS, insomnia, hypersomnia, and cramps. Usually I'm good at coping, and can at least put on a good front, but when the PMDD kicks in, I will want to tell my mother that I'm fine so that she doesn't worry, but the words physically won't come out of my mouth, because I'm convinced that I ham horribly not fine, and will never be fine again. I'm not one to take medicating myself lightly, certainly not psych meds, and I think the difference for me between PMDD and PMS, is that I'm willing to go there at this point, because otherwise for 1/4 of my life, I would be totally incapacitated.PMDD is still pretty controversial. Some doctors think it is a crock, and many think that Lilly made it up to sell more drugs to women who should just be coping with their PMS, that it is a case of overmedicatng to give prozac to women who snap at their husbands. I disagree. I don't just snap at people, I go off the deep end. I also think that it is understudied because, surprise, surprise - its a women's problem, and as much as we've progressed, many doctors and researchers still don't take women's problems seriously.As for what causes PMDD, no one knows, my guess is that it is a shift in the hormonal balance. I didn't used to have PMDD, but now I do.It does have its lighter moments. Once I cried at an episode of the Simpsons, because they were picking on Marge!