Illness related to the menstrual cycle is a substantial problem and available treatments are relatively ineffective. Women are to a greater degree than men affected by mental disorders, such as depression. One mechanism, instrumental in the progression of these disorders, is the impairing of the GABA system. PMDD is prevalent in ∼5% of all young and middle-aged women and includes severe cyclic symptoms. Affected women are thus periodically disabled with consequently reduced occupational productivity, decreased healthy-related quality of life and impairment of social relationships. Thus, the potential market for a new therapy in PMDD is substantial and include a target population of 3.7 million women in the US and 3.5 million women in the five largest European markets together.