Study finds key region of the brain is smaller in women who use oral contraceptives

By Sally Robertson, B.Sc.Dec 4 2019

A brain imaging study has shown that a key region of the brain was smaller among women who were taking oral contraceptives, compared with women who were not.

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The study, which found that women taking a birth control pill had a significantly lower hypothalamic volume, was presented today at the annual meeting of the Radiological Society of North America.

The hypothalamus is found at the base of the brain, above the pituitary gland. It secretes hormones involved in regulating important bodily functions such as heart rate, body temperature, sleep, appetite, mood and libido.

Structural effects of hormones on the hypothalamus have not been reported before

The researchers say the structural effects that reproductive hormones have on the hypothalamus (including the pill) have never been reported. They suggest this may be partly due to a lack of validated techniques for quantitatively analyzing MRI studies of the hypothalamus.

There is a lack of research on the effects of oral contraceptives on this small but essential part of the living human brain."

Michael Lipton, 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."

Oral contraceptives are one of the most popular forms of contraception

The birth control pill is one of the most commonly used forms of contraception. Oral contraceptives are also used to treat a range of health conditions such as menstrual cramping, irregular menstruation, acne, polycystic ovary syndrome and endometriosis.

According to a report by the Centers for Disease Control and Prevention's National Center for Health Statistics in 2018, approximately 47 million women (aged 15 to 49 years) in the United States reported current use of contraception between 2015 and 2017. Of those women, 12.6% said they used a contraceptive pill.

“A dramatic difference in the size of the brain structures”

For the study, Lipton and team recruited 50 healthy women, 21 of whom who were taking an oral contraceptive. All of the women underwent brain scans by MRI and the researchers used a validated method to measure hypothalamic volume.

"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 Lipton. "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."

The study, which Lipton described as "preliminary," also found that lower hypothalamic volume was associated with increased anger and was strongly correlated with depressive symptoms. The researchers did not find any significant correlation between hypothalamic volume and cognitive performance.