Premenstrual Dysphoric Disorder, otherwise known as PMDD, can be more easily understood as a more severe form of Premenstrual Syndrome, or PMS. In this manner, symptoms are stronger and longer-lasting, and tend to coincide with (and worsen) pre-existing mental health conditions, such as major depressive disorder, generalized anxiety disorder, and bipolar disorder. There is seen to be correlation between those with a history of trauma, physical or emotional abuse, and extreme stress who are diagnosed with PMDD, yet no specific causes (hormonal/physical) are fully known.