Every time I have a terrible day or find myself sobbing while listening to StoryCorps (fine, that happens every Friday morning), my first thought is: Am I PMS right now, or perhaps even PMDD? And the truth is (minus those StoryCorps mornings), I usually am. According to Redbook , PMDD (premenstrual dysphoric disorder), which is an extreme form of PMS, affects 2 to 5% of women. But a new study from the National Institutes of Health published in the journal Molecular Psychiatry shows that there might be a genetic connection to your PMDD. The study finds that there is a complex (sum of factors that characterize a condition) of genes that could show some women are more susceptible to major symptoms of PMDD, such as anxiety, irritability, and depression. The study did two things: It looked at how women who suffer from PMDD reacted to hormones with estrogen and progesterone “turned off,” and then it looked at those women’s white blood cells separately. With the hormones “turned off,” the women’s symptoms reportedly went away. The control group didn't see the same changes, which suggests that sensitivity to those hormones is a major part of PMDD. When looking at the women’s cells, Redbook reports that the gene complex of the women with and without PMDD reacted two different ways with the hormones present. In other words, there was an actual severe difference related to biology.