This is Your Brain on Hormones

**Lulu Miller** (0:02)
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**Pavel Shapturenka** (2:08)
Thank you.

**Lulu Miller** (2:09)
Okay.

**Pavel Shapturenka** (2:10)
All right.

**Molly Webster** (2:17)
Radiolab.

**Pavel Shapturenka** (2:17)
From WNYC.

**Molly Webster** (2:25)
One of the reasons that I come to you is maybe 10 or 15 years ago, I read a popular science book.
I'm not even going to say the title, because I think that it was like somewhat controversial afterwards. And I remember this fact, and I think since I read it, I have wondered if it was true. And I've also told everybody this fact. So this is like my live fact check, which is, I read that as you go through your menstrual cycle, the size or shape or makeup of your brain changes. And I remember reading that and thinking, wait, my brain actually physically is changing. Is that true?

**Emily Jacobs** (3:19)
Okay. There's so much to unpack here.

**Molly Webster** (3:27)
Hey, I'm Molly Webster. This is Radiolab. And today, I can go real far back.
We're going hard on a question that I have been thinking about for years.

**Emily Jacobs** (3:37)
Totally.

**Molly Webster** (3:38)
It's funny, as I've been thinking about this topic, everyone's like, honestly, you should just talk to Emily.

**Emily Jacobs** (3:43)
Oh.

**Molly Webster** (3:43)
Like, Emily is a neuroscientist, a neuroendocrinologist, to be precise, and she is on one of the teams that has been struggling to understand how hormones affect the brain.

**Emily Jacobs** (3:57)
Because we had these glimpses, these little flickers of what it could be doing. But to watch the full cinematic view of how this is unfolding, that was a breakthrough.

**Molly Webster** (4:13)
Very recently, Emily's lab came up with an experiment to so precise, so daring, it allowed them to pin down what hormones can do to our brains. Here's the thing, even though the story starts with menstrual cycles, it very quickly gets to the fact that women, men, whoever, we are all at the mercy of a crashing, swelling wash of chemicals inside of us.
The chemicals we call hormones.

**Emily Jacobs** (4:53)
So when we say a hormone, maybe we just define our terms, like when we say a hormone, that's a chemical messenger. It's a chemical that is released from an endocrine gland, like testes or ovaries. You have adrenal glands sitting on top of your kidneys. You have a thyroid gland.
And then once they start producing hormones, those hormones use your circulatory system, your blood supply as their super highway. They hit almost every cell in the body. And that's, when you think about like, why do we even have hormones? Like why is that a thing?