How does the pill affect your brain? We're finally getting answers

Oral contraceptives have been effectively preventing pregnancy for more than 65 years, but it has only been in the past 10 that scientists – many of them women – have started to seriously examine what effect they have on the brain.

New research is showing that oral hormonal contraceptives may alter the risk of mood disorders such as depression and anxiety, affect the brain’s response to stress and change the structure of certain brain regions. Evidence presented at the European Stroke Organisation Conference on 21 May also shows that women on oral contraception face a threefold increased risk of cryptogenic ischemic stroke, when a clot blocks the flow of blood to the brain.

So far, the science still suggests hormonal birth control is largely safe, but it has side-effects that vary with each individual, their age and health history, and the particular formulation of their contraceptive.

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Some of those trade-offs may be in mood. Several large studies have found higher rates of depression in oral contraceptive users, particularly in those just starting to take the pill. Those who display hormonal sensitivity, where abrupt changes in hormones – such as during puberty, pregnancy and the postpartum period – hit particularly hard, may be at a higher risk of negative effects. But the evidence suggests people’s responses are incredibly individual – some see their mood improve on oral contraceptives, and for others, using oral birth control methods for long periods reduces the risk of depression and anxiety.

“What has become increasingly clear is that it all depends,” says Adriene Beltz at the University of Michigan. Additionally, the different types of oral contraceptives further muddy the waters. The most common form, the combined oral contraceptive pill, contains both oestrogen and one of several kinds of progestin, which are synthetic forms of progesterone. Progestin-only pills, also called “mini-pills”, haven’t been as well studied, and the different kinds of progestin they use each act differently in the body.

Read the full article on NewScientist.