The prevalence of symptom cyclicity and premenstrual dysphoric disorder in randomly recruited samples of women has not been ascertained. We assessed this prospectively in 83 Icelandic women, aged 20-40 years, using and not using oral contraceptives (OCs).
A check list of 57 symptoms, divided into 7 symptom groups, was used to assess experiences. All symptoms and summarized symptom scores within symptom groups were tested for significant change between the follicular and the luteal phase of each menstrual cycle. When a symptom or a summarized symptom score was higher during the luteal phase compared to the follicular phase the cyclicity is labelled 'expected' cyclicity and the opposite 'unexpected' cyclicity.
The women charted from 1-7 menstrual cycles each, with 66 of them charting 3-4 cycles. Cyclicity was never displayed by 9.6% of participants; 80.7% displayed expected cyclicity and 72.3% unexpected cyclicity at least once. Cyclicity in somatic symptoms was most often demonstrated by participants. Expected and unexpected cyclicity in summary symptom scores in well-being and in psychoemotional symptoms was very similar among participants. There was not much difference in cyclicity between non OC users and OC users. Fifty-one percent of the participants were self-defined with premenstrual syndrome with 2%-6% of them meeting the criteria of premenstrual dysphoric disorder.
The normalcy of cyclicity found in this study might explain the high prevalence of premenstrual syndrome in many recall surveys. The importance of prospective daily ratings for establishing symptom cyclicity in women cannot be over emphasized.