Estrogen is both a reproductive hormone and a neuroactive hormone. It crosses the blood-brain barrier, binds to receptors throughout the brain, and regulates the neurotransmitter systems responsible for mood, anxiety, motivation, and cognition. When estrogen levels are stable, these systems function efficiently. When estrogen fluctuates or declines — across the menstrual cycle, postpartum, and during perimenopause — the mental health effects can be profound.

Progesterone is often described as a “reproductive hormone,” but its role in the body goes far beyond fertility and pregnancy. Progesterone affects menstrual cycles, mood, sleep, brain function, and overall well-being, and changes in progesterone levels can have real physical and emotional effects throughout a woman’s life.

PMDD is a severe form of premenstrual syndrome (PMS)