For those interested in why I changed my mind about the probable relationship between the menstrual cycle and cyclical symptoms- as physiological rather than ‘sex hormone-related’ per se:
To begin with, if you look at any review of recent clinical research on ‘PMS’ or ‘PMDD’, you will see that various trials since the 1980’s have established that the ‘sex hormones’, specifically oestrogen and progesterone, do not influence (mood-based or most physical symptoms (with the possible exception of breast swelling/ pain)) cyclical symptoms directly. i.e. the levels of these particular hormones found in ‘PMS’ patients are just as diverse as those who do not experience symptoms. Some clinicians still believe that there is an ‘indirect’ relationship i.e. that the sex hormones may interact with other hormones, especially neurotransmitters, resulting in symptoms in some people (who have some as yet unknown ‘sensitivity’ to such changes)- see the 2017 Royal college of Obstetricians and Gynaecologist’s ‘Green top guideline 48 on PMS’- https://www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg48/
However, no ‘causal’ relationship has been proven- meaning that cyclical symptoms only ‘might’ be triggered by indirect (sex) hormonal changes because the research has failed to identify the mechanism(s) by which this happens. Based on a high quality review of ‘mood studies’- Romans et al- http://einsteinlab.ca/wp-content/uploads/2016/07/7-Mood-and-the-menstrual-cycle.pdf– It is clear that actually, there is no conclusive evidence of a specific ‘premenstrual’ mood disorder in menstruating people. Not to say that nobody experiences symptoms premenstrually, but that when comparing data between men and women, or between phases of the menstrual cycle, there are often no statistically significant differences (aside from day of the week- we are typically all more stressed on Sundays and Mondays due to the Mon-Fri work week!). This casts SERIOUS doubt on the sex hormone explanation for cyclical symptoms- since there are substantial hormonal differences between menstrual phases and between men and women. So, I now prefer an alternative theory about the cause of cyclical symptoms- based on what physically happens to the body during the menstrual cycle. This idea is also ‘not proven’- even though it has been around in the form of ‘water retention explanations for PMS’ for over 90 years- so please do not quote me as any sort of reference. I just think it makes more sense as an explanation and deserves further investigation. For example, cyclical blood sugar changes could explain dizziness, changes in appetite, fatigue, headache/ migraine, and even trigger epilepsy-related seizures. Likewise, cyclical water retention could explain swelling, constipation, acne, weight gain, and thirst. Cyclical blood pressure changes could explain dizziness, feeling tense, and may even effect mood. All of these combined (plus pain, inflammation responses and blood loss) could definitely affect mood, since all humans experience irritability if hungry, tired, or in pain- especially when external factors annoy them! What is good about this explanation is that it complements what we already know about non-menstruating women and men’s experiences of these same symptoms- while they don’t have a menstrual cycle- they can experience blood pressure/ sugar changes, water retention, and anaemia/ pain etc. and subsequently experience the same symptoms that some women do on a cyclical basis. I am currently conducting research on this topic but it won’t be published until 2021. So, until then, it is just my opinion! I edited the blog to remove all the bits that I had previously attributed to ‘sex hormones’ so this version is the best I can offer until the research data are published.