PMS is a symptom pattern. PMDD is a diagnosis.
Premenstrual syndrome (PMS) is the constellation of physical and emotional symptoms most people notice in the week before their period — bloating, breast tenderness, irritability, low mood. Up to 75% of menstruators report some PMS.
Premenstrual dysphoric disorder (PMDD) is different. It's listed as a depressive disorder in the DSM-5 and affects roughly 3–8% of menstruators. The core feature is severe mood disturbance — not just feeling grumpy, but experiencing depression, rage, panic, or suicidal ideation, on a cyclical schedule.
DSM-5 PMDD criteria (simplified)
For a diagnosis, symptoms must be present in the final week before menstruation, improve within a few days after menstruation starts, and be minimal or absent post-menstruation — for at least two cycles.
- At least one core mood symptom
- Marked mood swings, marked irritability or anger, marked depressed mood, or marked anxiety.
- Plus additional symptoms totalling five
- Loss of interest, difficulty concentrating, lethargy, appetite change, sleep disturbance, feeling overwhelmed, physical symptoms.
- Clinically significant impairment
- Interferes with work, school, relationships, or social activities.
- Not just an exacerbation of another disorder
- Distinguished from major depression, generalised anxiety, or a personality disorder that happens to fluctuate.
The neuroscience
The leading theory is that PMDD isn't caused by abnormal hormone levels — it's caused by an abnormal brain response to normal hormone fluctuations. Specifically, sensitivity to allopregnanolone, a metabolite of progesterone that normally has calming effects via GABA receptors.
This is why PMDD isn't 'fixed' by hormone tests coming back normal. Levels are usually normal. The response is not.
Self-check
Quick check
1. PMDD is best classified as: