2.The prevalence of PMDD was measured using the research criteria identified by APA in DSM-IV-TR (APA 2000). Research criteria identified by DSM-IV-TR is the most common criteria used to diagnose PMDD (Smith et al. 2003). The research criteria indicated that, in most menstrual cycles during the past year, the presence of at least five symptoms (one of which must be affective) out of 11 during the last week of the luteal phase, which began to remit within few days after the onset of the follicular phase and were absent in the week post menses. The researchers provided the participants with a list containing the 11 symptoms and asked them to indicate which symptom has been experienced most of the time during the last year, and then participants were asked to confirm these symptoms prospectively during three consecutive symptomatic cycles. Those who met the diagnostic criteria were considered as having PMDD.