Birth control pills have some troubling possible side effects, including altering a woman's mood and even her choice of romantic partner. A new study adds another potential concern to the list: Hormonal contraception may shrink portions of the brain and affect their function.
It's possible that the synthetic hormones found in the Pill -- and possibly the suppression of natural hormones that occurs when women are using the Pill -- cause these alterations in brain structure and function, according to a new study published in the journal Human Brain Mapping.
In a study conducted on 90 women, neuroscientists at UCLA found that two key brain regions, the lateral orbitofrontal cortex and the posterior cigulate cortex, were thinner in women who used oral contraception than in women who did not.
The lateral orbitofrontal cortex plays an important role in emotion regulation and responding to rewards, while the posterior cigulate cortex is involved with inward-directed thought, and shows increased activity when we recall personal memories and plan for the future.
Changes in the lateral orbitofrontal cortex could be responsible for the increased anxiety and depressive symptoms that some women experience when they start taking the Pill.
"Some women experience negative emotional side effects from taking oral contraceptive pills, although the scientific findings investigating that have been mixed," Nicole Petersen, a neuroscientist at UCLA and the study's lead author, told The Huffington Post. "So it's possible that this change in the lateral orbitofrontal cortex may be related to the emotional changes that some women experience when using birth control pills."
Scientists have not yet determined if these neurological changes are permanent, or if they only last while a woman is on the Pill.
"We need to do more studies to find out what behaviors might be changed, but this study gives us some targets to start with, and I think the first place to look is at the effect of birth control pills on regulating emotions," Petersen said.
The new findings contradict a 2010 study that found that the Pill thickened brain areas associated with learning, memory and emotion regulation.
At this point, research on the Pill's neurological effects is limited, so it's difficult to draw conclusions. However, some scientists say that the preliminary research may give reason for caution.
"The possibility that an accepted form of chemical contraception has the ability to alter the gross structure of the human brain is a cause for concern, even if the changes seem benign -- for the moment," neuroscientist Craig Kinsey wrote in Scientific American about the 2010 study. "In any event, women need to have all of the medical and now, neurobiological, information they can use in informing their personal contraceptive decisions."