It’s common for women to feel slightly irritable, sad, or anxious before their period starts — a phase of the menstrual cycle called the “late luteal phase.” Out of balance hormones are to blame, right?
Not really, says a new brain imaging study.
In the February issue of Biological Psychiatry, UCLA researcher Andrea Rapkin reports on a brain scan study of women with premenstrual symptoms that are strong enough to qualify as premenstrual dysphoric disorder (PMDD) — which is characterized by more extreme mood swings and sadness right before menstruation. Women with PMDD are sometimes treated with an antidepressant.
Here’s what she found happening in the brains of women with and without PMDD:
Progesterone levels always rise in the late luteal phase (about one week before menstruation). But when Rapkin measured hormone levels of women with and without extreme mood symptoms, there was nothing noteworthy going on — levels were the same for both groups.
What she did find, is that an area of the brain called the cerebellum was extra active for those with PMDD. From previous animal studies, scientists know that progesterone alters receptors for the hormone GABA, which is like an off switch in the brain (or an “inhibitory molecule”).
In other words, it appears that women with PMDD have altered GABA receptors and can not get the “off switch” signal. That makes this area of the brain extra active — leading to anxiety and irritability.
So it’s not fluctuating hormones, it’s a change in how the brain processes those hormones during that particular week.
Do you have any notable mood symptoms like this? Have you been treated? Should women be treated for PMS?