Can Birth Control Thin Your Brain?

The advent of birth control has revolutionized the role of females in society: women now have control over when (and if) they want to have a family, allowing them to pursue meaningful careers and alternate paths. Furthermore, many hormonal birth control methods – which include the pill, the patch, the shot, the implant, the ring, two IUD’s, and emergency contraception – can offer relief for conditions such as endometriosis, polycystic ovarian syndrome, and acne; it can even alleviate symptoms of PMS and menstrual cramping. However, as with any medication, there are side effects, and hormonal contraception is no exception. In fact, a new study suggests it may change the structure and functioning of the brain.

The study, conducted by UCLA researchers Nicole Petersen et al and published in Human Brain Mapping, used MRI scans to compare “the cortical thickness of brain regions that participate in the salience network and the default mode network, as well as the volume of subcortical regions in these networks,” in women who use combination oral contraceptive pills (i.e. those containing both progestin and estrogen) versus naturally-cycling women. The researchers found that lateral orbitofrontal cortex and the posterior cingulate cortex were much thinner in women taking oral contraceptives. They note that, “These regions are believed to be important for responding to rewards and evaluating internal states/incoming stimuli, respectively.” The structural changes in the lateral orbitofrontal cortex in particular “could be responsible for the increased anxiety and depressive symptoms that some women experience when they start taking the Pill.” The researchers point out that their findings “do not and cannot provide any information regarding the effects of [oral contraceptive pills] on any behavior.” However, they conjecture that the neurological alterations they documented in users of the Pill may decrease the effectiveness of “effortful emotion regulation… [and] may influence response inhibition more generally.” It could also impact performance on “tasks that demand default mode network activation or deactivation, which may be beneficial, detrimental, or both, depending on task demands.” Finally, the authors of the study state that, “It is currently not known whether these effects appear immediately after initiating OC use, or gradually accumulate and increase over time. Further, it is not known how long these effects persist after OC discontinuation.”

The findings of this study conflict with prior research that suggested that the use of hormonal birth control resulted in an increase in grey matter thickness “in several brain regions when compared with naturally cycling women. These brain areas include the hippocampus, which is involved in learning and memory, and the fusiform face area (FFA), which is thought to be specialized for facial recognition.” The authors of the more recent study propose that these contradictory findings may have resulted from “differences in the study population, differences in the analysis techniques, or both.”

Further research has linked hormonal birth control to an increased risk for Crohn’s disease, glioma brain tumors, and ischaemic stroke (in women who experience migraine with aura). Given these potential risks, as well as the divergent nature of recent studies on birth control’s ability to exert changes in the brain, it is imperative that more research be conducted on the subject. As Craig H. Kinsley of Scientific American writes, “What happens, then, when the female brain gets a significant and artificial dose of steroid hormone, either progesterone, estrogen or both?  We know what happens below the waist, the pregnancies prevented.  What happens above the neck, as this steroidal tsunami washes over the neural coastline?” What happens, indeed – time will tell if our brains sink or swim through the deluge.

– By Betty Vine

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