2 Neuroscience2.11 Integrated neurobiology of syndromes and states
2.11.20 Menstrual cycle and mood
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Written by Resident Doctor Committee · Published
New in the 2027 syllabus
The College added this topic for exams from January 2027.
What it is
Premenstrual dysphoric disorder (PMDD) is a pattern of recurrent mood symptoms that cluster before menstruation. They improve once the period starts, and a relatively symptom-free interval follows.
Why it happens
Oestradiol and progesterone rise and fall across a normal cycle. In PMDD, blood levels of these hormones are not usually persistently abnormal. The problem seems to lie in how the brain responds to the change.
Allopregnanolone is a metabolite of progesterone. It acts on gamma-aminobutyric acid type A (GABA-A) receptors, the main fast inhibitory receptors in the brain. One proposed mechanism is altered sensitivity, or altered adaptation, to these changing neurosteroid signals.
Serotonin systems also interact with ovarian steroid signalling. This gives a second biological route by which cycle changes can affect mood.
Ovarian suppression and hormone add-back experiments support this model. They point to sensitivity to steroid change in susceptible people, not a simple lack of hormone.
Telling the patterns apart
Pattern | What it suggests |
|---|---|
Symptoms cluster in the luteal phase and resolve after menstruation | A premenstrual disorder, if confirmed by prospective ratings |
Symptoms are present all month but get worse before menstruation | Premenstrual exacerbation of an existing disorder |
New symptoms with no consistent link to the cycle | Look for another psychiatric, endocrine or medical cause |
Ask for prospective daily ratings over at least two cycles. These confirm the timing and separate a true recurrent cycle effect from blaming the cycle in hindsight.
When judging whether the cycle explains the pattern, look at functional impairment and symptom-free intervals as well as the type of symptoms.
Receptor adaptation is a model of mechanism, not a routine test. Measuring hormones in the blood does not confirm PMDD.