Women who use birth control pills have a significantly smaller hypothalamus volume, a region of the brain associated with anger and depression, than those who do not take oral contraceptive pills (OCPs), according to preliminary findings presented at the Radiological Society of North America (RSNA).
The hypothalamus is a small brain structure located just above the pituitary gland that's responsible for the production of hormones and the regulation of essential bodily functions, such as mood, appetite, libido, sleep, and body temperature. Previous studies have suggested that dysregulation of the hypothalamus in conjunction with other parts of the brain has been linked to depression. Other research has indicated that its stimulation may trigger aggression, anger, or fear.
For the current study, researchers acquired high-resolution MRI scans of 50 healthy women – admittedly a small sample size – 21 of whom were taking oral contraceptives at the time of imaging. A “dramatic difference” in the size of certain brain structures was observed between those who were and were not taking oral contraceptives. Study author Dr Michael Lipton, a professor at Gruss Magnetic Resonance Research Center at Albert Einstein College of Medicine and medical director of MRI Services at Montefiore Medical Center, told IFLScience it is possible there are other structural changes in the brain from oral contraceptives.
"Sex hormones have known (from animal studies) trophic effects on the central nervous system. Some results on brain structure have been reported, but none on the hypothalamus, which has a central role in the regulation of reproduction and endocrine function in general," he said.
Though the study is not yet published in a peer-reviewed journal, the authors note that characterizing the effects of oral contraceptives on the hypothalamus provides a “bridge to understanding functional alterations” associated with their use. Even so, determining how sex hormones like contraceptive pills affect the structure of the brain has not been reported previously, potentially because of an inability to analyze MRI scans in such a way, they noted. However, Lipton is quick to add caution to the study's findings.
"It is important to keep in mind that this study is just the first hint at an effect of OCPs on the hypothalamus. It is premature to extrapolate to a direct causative role of OCPs and certainly any causal link to specific physiological or behavioral effects," he said. "Those questions must be addressed in a larger prospective study that is specifically designed to address those specific questions."
OCP users should not be concerned based on the findings, he added. As with any hormonal drug, OCPs entail real risks that are determined by millions of women to be outweighed by the benefits, and it will take more research to reproduce and understand the clinical implications of the effects, if any.
Oral contraceptives are one of the most common forms of birth control and can be used to treat other conditions, including irregular menstruation, acne, polycystic ovary syndrome, endometriosis, and premenstrual dysphoric disorder (PMDD). Between 2015 and 2016, nearly two-thirds of women in the United States were using some form of birth control, according to the Centers for Disease Control and Prevention (CDC). Among US women between the ages of 15 and 44, almost 16 percent reported taking some form of an oral contraceptive pill.