For people with premenstrual dysphoric disorder (PMDD), the prelude to their period is a nightmare, filled with rage storms, clouds of depression, and rolling waves of anxiety. Then it all vanishes, only to come again the next month. Over 70% of people with PMDD have thought about suicide, and a third have attempted it.

For many people, treatment is straightforward and effective: birth control or an antidepressant. However, few people have heard of PMDD, including doctors, so many go untreated. In a 2022 survey, over a third of PMDD patients said their doctors had never heard of PMDD, and 40% said their mental health clinicians had never heard of it.

Worse, there are still many basic questions about PMDD that remain unanswered. What causes PMDD? Is there more than one type? Why do treatments work for some people but not others?

A new paper from Liisa Hantsoo at Johns Hopkins University and Jennifer Payne at the University of Virginia sheds light on why we know so little about PMDD. They found PMDD research receives 80% less funding from the government than postpartum depression, even though it impacts five times as many people.

Hantsoo and Payne ran the numbers. PMDD impacts an estimated 3 to 8% of all menstruators. Postpartum depression affects 12% of people giving birth each year. If you do the math using the conservative estimate of 3%, PMDD impacts 2.3 million women in the U.S. every year, and postpartum depression affects 440,130.

But Hantsoo and Payne also found there are only nine studies currently funded for PMDD while postpartum depression has 139.

“I go to a lot of conferences about women’s mental health,” says Hantsoo. “There’s a large focus on perinatal mental health, but nothing on menstrual or menopausal mental health . . . I got really curious about the funding rates.” In terms of dollars, PMDD is receiving $11 million, while postpartum depression studies have been awarded $60 million.

In their paper, Hantsoo and Payne also point out the number of people who suffer from menstrual mood disorders extends beyond PMDD. There are many people who may have PMS symptoms that aren’t severe enough to count as PMDD, but are still debilitating and worth treatment and further study.

Moreover, mental health disorders in women are frequently exacerbated by the menstrual cycle: At least 60% of women with depression also see their symptoms get worse prior to their period. Yet the researchers noted most journals tend to publish studies that focus on reproductive health and pregnancy.

“Postpartum depression is important but there’s more to women’s mental health than postpartum depression,” says Hantsoo. “There are a lot of other issues that deserve our attention as well.”

A spokesperson from the National Institute of Mental Health (NIMH) commented, “NIMH is committed to conducting and supporting research to better understand and address mental illnesses, including PMDD,” and provided a link to one study. (It’s worth noting some of the most influential research on PMDD has come from NIMH research labs.)

One reason behind the dearth of research might be a pipeline problem. If people don’t know about PMDD in the first place, fewer researchers might be proposing PMDD research projects to the NIMH. The NIMH did not provide numbers on how many PMDD research proposals they receive compared to postpartum depression projects, but Hantsoo guesses postpartum depression proposals significantly outnumber PMDD proposals. After all, if you don’t know something exists, how can you propose to study it?

That may make sense. But it’s cold comfort for the over two million women with PMDD who battle their emotions month after month to hang onto their relationships, their livelihoods, and their lives.