Is it that time of the month? These are the words no man should ever utter. How about this for a diplomatic alternative: “Are your GABA receptors playing up?”
You may be spot on. It seems that these brain cells are to blame for some women’s monthly mood swings.
Symptoms of what’s called premenstrual dysphoric disorder (PMDD) begin around a week before menstruation when women are in the “late luteal phase” of their cycle and progesterone levels are at their height. Symptoms quickly subside after menstruation, once the so-called “follicular phase” has kicked in.
To investigate potential mechanisms behind PMDD, Andrea Rapkin at the University of California, Los Angeles used a PET scan, which shows where glucose is being metabolised to identify activity in the brain. The idea was to analyse the brain activity of 12 women with PMDD and 12 without the condition, at various times throughout their menstrual cycle.
Fluctuating hormones were not to blame: all the women experienced similar jumps in progesterone levels throughout their cycle, irrespective of whether they had PMDD or not.
However, brain analyses showed that in the late luteal phase women with PMDD had heightened activity in their cerebellum. Rapkin also discovered that the larger the spike in activity, the worse the symptoms.
Women without PMDD had no such spike in activity, even though their progesterone levels were also rising during this time.