New York—A recent finding that, in women taking oral contraceptives, hypothalamus volume is significantly smaller compared with women not taking birth-control pills could have far-reaching implications.

A study presented at the annual meeting of the Radiological Society of North America points out that structural effects of sex hormones, including oral contraceptive pills, on the human hypothalamus have not previously been reported. The hypothalamus produces hormones and helps regulate essential bodily functions including body temperature, mood, appetite, sex drive, sleep cycles, and heart rate.

“There is a lack of research on the effects of oral contraceptives on this small but essential part of the living human brain,” explained Michael L. Lipton, MD, PhD, professor of radiology at the Gruss Magnetic Resonance Research Center 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 the volume of the hypothalamus and confirm, for the first time, that current oral contraceptive pill usage is associated with smaller hypothalamic volume.”

Researchers suggest that limited evidence exists on the structural and functional effects of hormonal contraceptives on the brain, adding, “In particular, these effects on the hypothalamus are not known. In this study, we aim to identify alteration of hypothalamic volume associated with oral contraceptive pill (OCP) use in healthy women.”

High-resolution MRIs of the brain at 3T for a prospective cohort of 50 healthy women were acquired, with psychometric tests (Cogstate and PROMIS) administered at the time of imaging. Oral contraceptives were used by 21 participants at the time of imaging.

The study determined that total hypothalamic volume in participants taking OCPs was smaller than those not taking OCPs (b = -63.4 ± 22.2, P = .006). “There was a significant association of hypothalamic volume with greater anger (P = .02) as well as a strong correlation with depression (P = .09),” the authors write. “However, no significant correlation was found between hypothalamic volume and cognitive testing results.”

Background information in the study notes that oral contraceptives are among the most popular forms of birth control and are also used to treat a host of conditions, including irregular menstruation, cramps, acne, endometriosis, and polycystic ovary syndrome. It cites a 2018 report from the CDC’s National Center for Health Statistics that, from 2015 to 2017 approximately 47 million women aged 15 to 49 years in the United States reported current use of contraceptives. Of those, 12.6% used the pill.

“We found a dramatic difference in the size of the brain structures between women who were taking oral contraceptives and those who were not,” said Dr. Lipton, who calls the findings “preliminary.”

“This initial study shows a strong association and should motivate further investigation into the effects of oral contraceptives on brain structure and their potential impact on brain function,” he adds.

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