Birth control pills ‘alter the structure of women’s brains’ which could make them angry or depressed A study has found that women taking oral contraceptives had a smaller hypothalamus than women not taking the pill

Birth control pills may alter the size of a small part of women’s brains, which could be making them angry and depressed – but does not affect their intelligence, according to a small study.

Women taking the oral contraceptive were found in the study to have a smaller hypothalamus than women not taking the pill. The hypothalamus is a pea-size structure deep inside the brain that helps regulate involuntary functions, such as appetite, body temperature and emotions. It also serves as a link between the nervous system and endocrine system, a network of glands that produce hormones.

The new study, not yet peer-reviewed and presented at the annual meeting of the Radiological Society of North America, found that, on average, women taking the pill had a hypothalamus that was about 6 per cent smaller than it was in women not taking the pill.

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Dr Michael Lipton, professor of radiology at the Albert Einstein College of Medicine in New York, who led the recent research, said: “For a brain region, that’s a pretty sizeable difference.”

To gauge the structure’s volume, the researchers used MRI scans of 50 women, 21 of whom were taking a combination pill — a common type of birth control pill that provides a dose of synthetic oestrogen and progestin. The team also had the women complete online interviews and tests to assess aspects of their mood, personality and cognitive functions.

The study shows that women taking the pill do not have smaller brains overall and that their mental abilities are not affected. However, the researchers did find that a smaller hypothalamus is associated with increased anger and symptoms of depression.

Dr Lipton accepted that the study has yet to be peer reviewed, the findings were preliminary and that it is too early to conclude how oral contraceptives affect the brain, if at all. “We’re not saying that people should run out and throw away their birth control pills. If anything, the results may simply point to a question that warrants more research,” he said.

Cautionary note

Several UK-based scientists all urged caution with the preliminary findings.

Christopher Petkov, professor of comparative neuropsychology at Newcastle University, said: “I would be very careful about concluding that oral contraceptive use is associated with smaller hypothalamic volumes from this preliminary work being presented at a scientific meeting for the authors to discuss with the scientific community as they work towards completing their study.”

Derek Hill, professor of medical imaging at UCL, said: “Results like this are intriguing but must be treated with caution. Firstly, small studies like this are susceptible to ‘false positives’ – that is random findings that would disappear in a larger study.

“Secondly, it isn’t clear from this work whether the authors only studied the hypothalamus, or examined many brain structures and this one was significantly different between the group, which could increase the chance of false positive findings. Thirdly, even if the difference in volume is real, it doesn’t mean that the contraceptive pill has damaged the brain.”

Dr Lipton acknowledged it is still too early to conclude how oral contraceptives affect the brain, if at all. “We’re not saying that people should run out and throw away their birth control pills. If anything, the results may simply point to a question that warrants more research,” he said.

The researchers claim the study was the first of its kind, but this was called into question by UK academics who told i there has been plenty of research in this area. Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said: “There is lots of research on whether oral contraceptives affect the brain through studying clinical effects in large numbers so to say the research is ‘sparse’ is not the full picture.”

More than 50 years since it became widely available in the UK, the pill remains the most popular form of prescribed contraceptive among women in the UK. Recent figures obtained under the Freedom of Information Act show almost nine in 10 women who receive contraception from the GP or pharmacies take either the combined pill or “mini pill” – a total of more than 3.1 million women in England in 2017-18 – with the proportion remaining similar for the past three years. Yet despite their widespread use, research looking at how oral contraceptives affect the brain is sparse.