What actually causes PMDD?

Short answer: your hormones are usually normal. The problem is a heightened brain response to the normal rise and fall of ovarian hormones—especially in the late luteal phase (the week before bleeding).

Researchers showed this by doing a simple but powerful test. When they temporarily paused ovarian hormones, PMDD symptoms faded. When they added the same hormones back (normal doses of oestradiol and progesterone), symptoms returned only in women with PMDD, not in women without it. So PMDD isn’t “too much hormone”—it’s how the brain reacts to the change.

The brain systems involved (in plain English)

1) Hormone sensitivity, not hormone excess

Your ovaries do their usual monthly dance. In PMDD, the brain is extra sensitive to that dance, like a volume knob turned up too high.

2) The GABA “calm system” and allopregnanolone (ALLO)

Progesterone breaks down into a brain chemical called allopregnanolone (ALLO). ALLO usually supports GABA-A receptors, which help us feel calm.

In PMDD, ALLO’s signal can flip in the late luteal phase. Instead of steadying mood, it can make you feel tense, low, rage-y, or foggy. Trials that block ALLO’s effect (with a medicine called sepranolone) improve core PMDD symptoms. Other research shows that reducing ALLO’s rise can also help. That’s strong evidence that ALLO and GABA are key players.

3) Serotonin and timing

Many women with PMDD improve quickly with SSRIs (a type of antidepressant), even if taken only in the luteal phase or started right at symptom onset. That fast response tells us the timing of serotonin support matters. Some brain scans also show cycle-linked changes in the serotonin system that line up with symptoms. We can achieve the same, but using natural medicine if you would prefer to go down that path.

4) The stress system (HPA axis)

Women with PMDD often show a blunted cortisol response to stress in the late luteal phase. In simple terms, the stress alarm doesn’t rise and fall in a healthy rhythm. This can make everyday stressors hit harder that week—even small things, like a messy kitchen or a sharp email. This is why when we work together, we work to powerfully support your HPA axis and nervous system.

5) Sleep, body clock, and inflammation (emerging science)

Some studies suggest small shifts in inflammatory markers and body-clock genes around symptom days. This helps explain why poor sleep, late nights, and heavy alcohol can make the luteal phase feel worse. (Yes, coffee helps you feel awake, but sleep helps you feel human.)

In Summary: Normal hormone waves meet a brain that is extra sensitive—especially in GABA and serotonin systems—and a stress axis that’s a bit off-beat. That mix creates the classic late-luteal mood, energy, and thinking symptoms.