When the study’s authors examined high-resolution images of participants’ brains, they found the women on hormones showed more matter in some areas of the brain, including the prefrontal cortex, which is associated with cognitive activities like decision-making.
The Brain Research study prompted breathless news reports suggesting that the pill makes you smarter. But Kinsley and Meyer point out that the brain works like a “neural beehive,” and disturbing one part of the hive could impact the other. The fact that one brain region becomes larger than the next does not mean a woman on hormones is more intelligent or effective. It is also possible that her brain is going haywire. (Kinsley and Meyer actually use the word “catawampus.”) 
- http://www.popsci.com/science/article/2010-09/birth-control-pills-shown-alter-structure-womens-brains [↩]