Misstropolis

Wednesday, March 07, 2007

Hormones are so…Rewarding

by Rachael Moeller Gorman

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A new study from the National Institutes of Health confirms exactly what we already know: our menstrual cycles have a very personal agenda with our brains. Aside from playing with our mood and tweaking our sensitivity to pain, our cycles, it seems, can also make the good things in life – money, food, sex – feel more intensely rewarding on certain days of the month. This research could someday help doctors conquer drug addiction and mood disorders, and just as importantly, mollify women’s bafflement over the invisible pendulum making some days wonderful and others bad or blah.

Scientists already had some idea that rewards and hormones were connected. Female rats will self-administer more cocaine at different times of their cycle than others – they get more of a kick from the drug when their estrogen is high, so they keep pushing that little paw-sized lever. Women also seem to respond more strongly to cocaine and amphetamine during their follicular phase (pre-ovulation) than the luteal phase (post-ovulation). 

But in this study, researchers actually watched women’s brains in real time to see what went on as they played a gambling game. The scientists already knew which brain regions are involved in anticipation and receipt of rewards like gooey homemade cookies or hugs from a child, so they hooked the 13 female subjects up to a functional MRI (fMRI) machine and scrutinized just those reward areas during different phases in the women’s cycles (the women played a video slot machine game and were told they’d receive a percentage of the $10 or $20 winnings if the right symbols popped up.)

The team found that both anticipating a big gambling payoff and winning the money flipped on the reward circuitry of the brain much more strongly during the midfollicular phase – days 4-8 after the onset of your period – than the luteal phase.

Hormones are the culprits. The researchers believe that because estrogen is unopposed by progesterone early in a woman’s cycle (its levels don’t rise up until after ovulation) estrogen is able to turn on the reward areas of the brain. This makes sense in evolutionary terms, the authors write, since, “the increased availability, receptivity, and desire that may occur during the ovulatory period has been thought to facilitate procreation.” In other words, feeling great during that special time of the month may make you and your partner more likely to tuck the kids in early and get those hormones jitterbugging with your partner.

Researchers still need to figure out exactly what this means for women on hormone replacement therapy and birth control, as well as those addicted to drugs or gambling; but its good to see the NIH putting their research dollars toward something women have endured since, well, since Eve first got pissed at Adam for not really listening to her Big Bang story. For now, try booking a dinner at your favorite restaurant or planning a sleepover at grandma’s for the kids during those special days; you’ll get way more bang for your buck.

For a woman, every day feels a little bit different – aren’t we lucky.