Premenstrual Syndrome (PMS) is truly a puzzle. It has been written about since at least the early Greeks, recognized in medical contexts for centuries, and documented and studied in rural and urban women the world over (Asia, Africa, Europe, Australia and the Americas). Prevalence estimates range between 8 and 90 percent of women affected, and between 3 and 40 percent incapacitated by PMS each month. The true prevalence of PMS is difficult to determine for a variety of reasons, including self-treatment and differences in treatment-seeking behavior, cultural factors, discrepancies in medical access, and differences in definitions and diagnostic practices. No definitive test exists for PMS. No etiological agent has ever been found; and no underlying proximate mechanism has been revealed. There are currently over 65 different instruments used for assessing PMS, and over 150 symptoms associated with the syndrome. Moreover, standard definitions and diagnostic criteria differ greatly between authorities (DSM and ICD), and even more between physicians. Thus, women with nothing in common but their gender can be diagnosed with the same syndrome! In essence, we all know that PMS is real, and we recognize it when we see it or experience it, but no one knows what it really is.
Associate Professor Chris Reiber is investigating PMS within an evolutionary paradigm. The changes associated with PMS may be part of a larger, adaptive cycling of biopsychosocial characteristics across the menstrual cycle. Evolutionary forces appear to buoy women up during the ovulatory phase of the cycle. For instance, during the fertile phase of the menstrual cycle, women ornament more and wear sexier/bolder clothing, go to clubs more, are more attentive to "maleness", increase ranging activities including locomotion and volunteering for more social activities, and flirt more with men not their mates.
Physical and chemical changes also track the menstrual cycle. Women's facial appearance and body odors are more attractive to men during the fertile phase of the menstrual cycle. Finally, women's sexual desire is reported to be higher during the fertile phase than during non-fertile phases of the menstrual cycle. These phenomena have been interpreted as evolutionarily adaptive strategies to maximize chances of mating and fertilization. Hence, they fluctuate in tandem with the menstrual cycle, being most pronounced when the possibility of mate attraction and fertilization is greatest, and abating thereafter.
In essence, women's sociobehavioral state of being cycles "up" and "down" across the menstrual cycle. During the fertile phase of the menstrual cycle, women are more social, more active, feel sexier and more flirtatious and desirous; they feel better, and men find them more attractive. When fertilization is no longer possible, these positive states abate. In contrast to the highs during the fertile phase of the cycle, the premenstruum brings a relatively lower state in which women are less social, less active, feel less sexy and less flirtatious and desirous; they feel relatively worse, and men find them less attractive. Taken together, these define a state of suboptimal general well-being, and may be subjectively experienced as symptoms. In its extreme, clinical form, this lower state is PMS.
Reiber's ongoing research continues to investigate this hypothesis. She is collecting a priori self-reports of PMS and symptoms, and prospective symptom ratings from women, as well as daily saliva samples. In collaboration with Yale University's Center for Human and Primate Reproductive Ecology (CHaPRE), the saliva samples are being analyzed for progesterone and estradiol. These data will allow her to evaluate the evolutionary model and examine the relationships between the model components, symptoms, and progesterone and estradiol levels. This is important because, while previous research exploring the role of sex hormones in PMS has failed to find any significant or explanatory relationships, it has been carried out without the benefit of an ultimate theoretical framework to guide the exploration.
Continuing work on this topic will include investigations of whether and how the impact of differing environmental and ecological stressors on sex hormones may affect the experience of PMS, and the cross-cultural patterns in the relationships between hormonal states, evolutionary predictors of symptomatology and PMS epidemiology.
Last Updated: 8/21/12