As with PMS, women with premenstrual dysphoric disorder (PMDD) regularly develop negative mood symptoms before their periods. Some experts consider premenstrual dysphoric disorder to be a severe form of PMS.
In PMDD, mood symptoms are more severe and often overshadow physical symptoms. The emotional disturbances are significant enough to cause problems with daily life. From 3% to 9% of women experience premenstrual dysphoric disorder.
Estrogen appears to be involved in these mood disturbances, but exactly how is more of a mystery. Estrogen levels in women with PMS or PMDD are almost always normal. The problem may instead lie in the way estrogen "talks" to the parts of the brain involved in mood. Women with PMS or PMDD may also be more affected by the normal fluctuations of estrogen during the menstrual cycle.