Radiolab
Radiolab

This is Your Brain on Hormones

June 19, 2026

AI Summary

5 min read

This is Your Brain on Hormones

For years, neuroscientist Emily Jacobs had been watching the field struggle with a basic question: do hormones actually change the brain? The evidence was tantalizing but thin—glimpses and flickers, never the full cinematic view. Then a graduate student named Laura Pritchett walked into her lab at UC Santa Barbara and said she wanted to answer that question by becoming the experiment herself. "I have normal cycles, I have a summer to kill, I don't really have a life," Laura told Emily. "I volunteer to do this."

The 28-Day Brain

The problem with most hormone-brain research, Emily explains, is that it takes a single snapshot. But hormones don't work that way. "A fundamental feature is that it ebbs and flows over time. It is not static," she says. "All of its power comes from the dynamism of that system. My body doesn't care if I'm at 20 picograms per milliliter of estradiol, it cares that I came from zero and I'm going to 200."

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What you'll learn

  • 1 (01:52) **The Central Question** - Molly introduces her decade-old question about whether the brain physically changes across the menstrual cycle
  • 2 (03:07) **Meet the Expert** - Introduction to neuroendocrinologist Emily Jacobs and the gap in understanding hormone effects on the brain
  • 3 (04:18) **What Hormones Actually Are** - Basic definition of hormones as chemical messengers traveling through blood
  • 4 (06:27) **Limits of Existing Hormone Research** - Current studies rely on single time-point snapshots and group averages
  • 5 (07:39) **Inspiration from Russ Poldrack** - The shift toward dense, repeated scanning of single individuals
  • 6 (08:38) **Laura Volunteers** - Graduate student Laura Pritchett offers herself as the subject for a 28-day study
  • 7 (10:51) **The 28 Me Protocol** - Daily saliva, blood draws, and MRI sessions across one full menstrual cycle

+ Full timestamped outline available in the app

Show Notes

After reading something that said her menstrual cycle changes her brain each month, Senior Correspondent Molly Webster goes on a reporting mission to see if that’s true, and, if so, how.

This journey into sex hormones and the brain involves females and males, and exacting self-experimentation. It gets into PTSD, and ends with a new twist on self-care (hint: it’s biological). And, it starts to reveal a sneaky truth: that each one of us is at the mercy of a crashing sea of chemicals inside of us – those things we call hormones.

Special thanks to Emily Jacobs, Laura Pritschet, Pavel Shapturenka, and Dr. Catherine Woolley.

EPISODE CREDITS:
Hosted by - Molly Webster
Reported by - Molly Webster
Produced by - Mona Madgavkar
with help from - Molly Webster
Fact-checking by - Diane A. Kelly

EPISODE CITATIONS:

Articles - 
**The experiments we feature in this episode are called: 28andMe, 28andOC, and 28andHe, all of which took place at Emily Jacobs lab at the University of California, Santa Barbara.** 

  • The 28 Project (https://zpr.io/CSx6MnwZjRvp), background from the Jacobs lab

For more on how much variability there is between female and male animals, check out this “groundbreaking” study, referenced by Emily Jacobs in our episode

Dr. Catherine Woolley has revolutionized the field of neuroscience and sex hormones, here’s more about her work …


Data sets -