The truth about whether 'period brain' really exists

The week of your period, you may be a bloated, crampy, hangry mess (we feel you).

But any mental missteps that happen have nothing to do with your flow. At least, that’s according to a new study published in Frontiers in Behavioral Neuroscience.

Swiss researchers followed 68 womens’ menstrual cycles for two months, looking to see if fluctuatinglevels of the hormones estrogen, progesterone, and testosterone had any impact on cognitive function. Throughout their cycles, study participants were put through a battery of psychological tests to measure three things: memory, cognitive bias (our tendencies to think a certain way, even if it isn’t rational), and the ability to pay attention to two things at once.

What the scientists found: Shifting hormones had no impact on the participants' mental prowess. Even when a woman had cognitive hiccups during one cycle, she often didn’t during the next.

“This study clearly demonstrates that most women do not have trouble thinking because their hormones change in a cyclical way,” says Tory Eisenlohr-Moul, Ph.D., a clinical psychologist who studies women’s emotional, cognitive, and behavioral responses to changing hormones across the menstrual cycle at the Center for Women's Mood Disorders at the University of North Carolina at Chapel Hill.

And it’s also an awesome, science–backed middle finger to any sexist dimwit who jokes that bleeding out your whatever dampens your mind. “Females get questioned because of the menstrual cycle but no one questions men, even though we know that shifting testosterone cycles are associated with some decision-making biases,” says researcher Katja Schmalenberger, M.S., who studies the cognitive effects of the menstrual cycle at the Institute of Medical Psychology at Heidelberg University, Germany.

However, there is a BIG caveat to this which is important to keep in mind if you do experience brain farts around your period.

"There is a group of women with mild to moderate or inconsistent changes in their thoughts and feelings across the cycle and maybe [current] tests just aren’t sensitive enough to see those," says Eisenlohr-Moul. Mary Jane Minkin, M.D., a clinical professor in the Department of Obstetrics, Gynecology, and Reproductive Sciences at the Yale University School of Medicine in New Haven, Connecticut, agrees. "In 40-plus years of taking care of women I think there are changes within a menstrual cycle, some of which can be attributed to hormones, some to other things," she says. For example, as estrogen and progesterone levels decline a day or two before your period starts, you may not sleep well. And "sleep deprivation can effect cognitive function the next day," says Minkin.

Research has already ID'd one group of women who do have abnormal mood and cognitive responses to hormone changes—those with premenstrual dysphoric disorder (PMDD), a debilitating condition that effects roughly 5 percent of women and causes significant anxiety, depression, irritability that can interfere with work or daily life, says Minkin.

Indeed, in a recent study of women with PMDD, Eisenlohr-Moul and Schmalenberger found women who had extreme emotional changes across their cycles also had cognitive changes, and that these changes in their ability to concentrate and solve problems had the biggest impact on their ability to work, maintain relationships, and engage in social activities.

Meaning: if you do have mental hiccups in the week around your period, tell your gynecologist. She’ll likely ask you to chart your daily symptoms over a few cycles to see if they fit the criteria for PMDD, says Minkin. The Gia Allemand Foundation, a non-profit that offers information on the condition and support for sufferers, has a downloadable symptom-tracker that can make this easier, notes Eisenlohr-Moul.

If you are diagnosed with PMDD, the fix can be as simple as taking certain birth-control pills that are approved to regulate mood, or a class of antidepressant called selective serotonin reuptake inhibitors (SSRIs). “Instead of taking the SSRI all the time, most women can just take it for the week or so around their period,” says Minkin.