A brain region known as the hypothalamus is smaller in women who use birth control pills compared to non-users, according to a new study. The study discovered that women who used the pill or oral contraceptives had a smaller hypothalamus than women who did not use the pill. The hypothalamus is a pea-sized structure deep within the brain that aids in the regulation of involuntary functions such as appetite, body temperature, and emotions. It also connects the nervous system to the endocrine system, which is a network of glands that produce hormones.
According to a new study presented today at the annual meeting of the Radiological Society of North America, women taking oral contraceptives, also known as birth control pills, had significantly smaller hypothalamus volume compared to women who did not take the pill (RSNA).
The hypothalamus, which is located at the base of the brain above the pituitary gland, produces hormones and helps regulate vital bodily functions such as body temperature, mood, appetite, sex drive, sleep cycles, and heart rate.
There is a paucity of research on the effects of oral contraceptives on this small but vital part of the living human brain. We validated methods for assessing hypothalamic volume and confirm, for the first time, that current oral contraceptive pill use is associated with lower hypothalamic volume.
Michael L. Lipton
According to the researchers, the structural effects of sex hormones, including oral contraceptives, on the human hypothalamus have never been reported. This could be due to the lack of validated methods for quantitatively analyzing hypothalamic MRI exams.
“There is a paucity of research on the effects of oral contraceptives on this small but vital part of the living human brain,” said Michael L. Lipton, M.D., Ph.D., FACR, professor of radiology at Albert Einstein College of Medicine and medical director of MRI Services at Montefiore Medical Center in New York City. “We validated methods for assessing hypothalamic volume and confirm, for the first time, that current oral contraceptive pill use is associated with lower hypothalamic volume.”
The findings are not surprising given that the hypothalamus produces hormones that regulate the body’s endocrine system, according to Jonathan Schaffir, associate professor of obstetrics and gynecology at The Ohio State University who was not involved in the study. Birth control pills may be signaling to the hypothalamus that it is not necessary to produce these hormones. In fact, previous research has shown that sex hormones promote the growth of neurons, according to Lipton. One theory is that the synthetic hormones found in oral contraceptives interfere with these effects, resulting in decreased brain cell growth.
Oral contraceptives are among the most widely used methods of birth control and are also used to treat a variety of conditions such as irregular menstruation, cramps, acne, endometriosis, and polycystic ovary syndrome. According to a 2018 report from the Centers for Disease Control and Prevention’s National Center for Health Statistics, approximately 47 million women aged 15-49 in the United States reported current use of contraception from 2015 to 2017. 12.6 percent of those tested positive for the pill.
Dr. Lipton and colleagues recruited 50 healthy women for their study, including 21 who were using oral contraceptives. All 50 women had brain MRIs, and hypothalamic volume was measured using a validated method.
“We discovered a significant difference in the size of brain structures between women who used oral contraceptives and those who did not,” Dr. Lipton said. “This preliminary study demonstrates a strong association, which should motivate further research into the effects of oral contraceptives on brain structure and their potential impact on brain function.”
Other preliminary findings from the study, according to Dr. Lipton, were that smaller hypothalamic volume was associated with greater anger and had a strong correlation with depressive symptoms. The study, however, discovered no significant relationship between hypothalamic volume and cognitive performance.
Indeed, the effects of oral contraceptives on the brain are not well understood. According to Nicole Petersen, a neuroendocrinology researcher at the University of California, Los Angeles, who was not involved in the study, a growing body of evidence, including the current study, suggests that there are differences in the volumes of certain brain regions in women on birth control pills. However, findings on this topic haven’t always been consistent — some studies show that women on the pill have smaller brain structures, while others show that they have larger or similar-sized structures, she says.
It’s still too early to tell how, if at all, oral contraceptives affect the brain, according to Lipton. “We’re not advocating that people throw away their birth control pills,” he clarified. If anything, the findings may simply point to a question that requires further investigation, he added.
“Our study’s goal is not to scare women or discourage them from using oral contraceptives.” We simply want to provide them with information so that they can make an informed decision about what is best for them. To fully understand the impact of oral contraceptives on women’s health, much more research is needed.”
