Symptoms associated with borderline personality disorder (BPD)—a severe and chronic mood disorder characterized by an inability to manage strong emotions—tend to worsen just before and during menses, according to a study in Psychological Medicine.

BPD is a mental illness marked by an ongoing pattern of varying moods, self-image, and behavior, according to the National Institute of Mental Health. These symptoms often result in impulsive actions and problems in relationships. People with BPD often experience intense episodes of anger, depression, and anxiety that can last from a few hours to days. Recurrent thoughts and behaviors related to self-injury or suicide are also common, and approximately 10% of people with BPD die from suicide.

“Our study provides the first evidence that females with BPD are at risk for worsened symptoms during the perimenstrual window of their menstrual cycle—the week before and during menses,” said Tory Eisenlohr-Moul, assistant professor of psychiatry at the University of Illinois at Chicago and lead author on the paper. “This is particularly important since people with BPD are at a high risk of suicide, so anything that can help patients and clinicians reliably predict changes in their symptoms is very useful.”

Eisenlohr-Moul and her colleagues wanted to investigate whether the menstrual cycle might be a contributing factor to the instability of symptoms associated with BPD in females.

“While we didn’t expect females with BPD to have higher or different hormone levels over the course of the menstrual cycle compared to those without the disorder, we suspect that, similar to females who suffer from severe premenstrual syndrome, women with BPD may simply be more sensitive to normal hormone changes, which we do know have an effect on mood,” Eisenlohr-Moul said.

The researchers recruited healthy women with normal menstrual cycles between the ages of 18 and 45 who were not taking any psychiatric medications or birth control. Of the 310 females who met the original screening criteria, 17 met the criteria for BPD, and 15 women ultimately completed the study. This is the largest prospective study examining cyclical mood changes in patients with BPD to date.

Participants completed several questionnaires at the beginning of the study related to borderline personality symptoms, past traumas, demographics, anxiety and depression, and menstrual cycle symptoms. Participants kept a record of daily symptoms related to BPD and menstruation for 35 consecutive days. Urine tests for luteinizing hormone and saliva tests for progesterone were used to confirm ovulation and track the phases of the menstrual cycle.

The researchers used the Carolina Premenstrual Assessment Scoring System, a questionnaire for evaluating clinically significant menstrual cycle effects on emotional symptoms, to evaluate whether the patients showed cyclical mood changes large enough to impact their day-to-day functioning.

The researchers found that most symptoms attributable to BPD were significantly exacerbated in the week before and during menstruation. “Symptoms, on average for the females in our study, worsened by at least 30% during the perimenstrual phase,” said Eisenlohr-Moul. “This is equivalent to going from moderate depression to extreme depression on the rating scale.”

For a patient population where almost every day is a difficult day in terms of coping with mood and stress, a 30% worsening of symptoms is a very significant uptick, explained Eisenlohr-Moul. “Because this group is at such a high risk for suicide, knowing that things get even worse for them during this time of the month around onset of their period, is a piece of information that we can work with to help prepare patients for a time when we know, based on solid research, that things could get worse.”

The perimenstrual phase of the cycle may be risky for people with BPD because levels of estrogen and progesterone fall off rapidly, according to Eisenlohr-Moul.

“For some women, or individuals who are freely cycling independent of their gender identity, it may be as though the plug is being pulled on these hormones that we know can help regulate mood,” she said. “Stable levels of estrogen and progesterone can improve mood and have an anti-anxiety effect. When these drop so precipitously around menses, it’s not surprising that some women with trouble regulating mood and emotions have an even harder time.”

Eisenlohr-Moul hopes to investigate the impact of hormone-stabilizing treatment on BPD symptoms in women in the future. “If we can smooth out the hormonal peaks and valleys over the course of the month, it would be interesting to see if we can reduce emotional symptoms by eliminating those hormonal triggers,” she said.