Birth control pills appear to remodel brain structure
It seems that weekly we hear about some professional athlete who sullies himself and his sport through abuse of steroids. The melodrama unfolds, careers and statistics are brought low and asterisked, and everyone bemoans another fallen competitor. Yet there are millions of cases of steroid use that occur daily with barely a second thought: Millions of women take birth control pills, blithely unaware that their effects may be subtly seeping into and modulating brain structure and activity.
It is a huge experiment whose resolution will not be known for a while, but a new study in the journal Brain Research demonstrates that the effects are likely to be dramatic. It found that birth control pills have structural effects on regions of the brain that govern higher-order cognitive activities, suggesting that a woman on birth control pills may literally not be herself — or is herself, on steroids.
The human brain is a remarkable structure, not least because of its seemingly infinite capacity for change, adapting millisecond by millisecond. Indeed, a structure with tens of billions of neurons, each of which has the ability to elaborate and branch and become more complex, while changing its activity in the process, is the very definition of change. This so-called neuroplasticity is a hallmark of the nervous system. It can, however, be augmented, boosted, by artificial means, and if we are not careful, the brain may go all catawampus.
Steroid hormones, which are excreted by endocrine organs such as testes and ovaries, flow in abundance throughout the bloodstream, reach target organs and structures, and exert powerful effects on them. To wit, the cock’s comb, the buck’s antlers, the lion’s mane, the blood-engorged uterus.
What of the mammal’s nervous system? It turns out that the brain is a veritable sponge for steroid hormones. In the male, the androgen testosterone (or a metabolite) binds to brain receptors and sculpts that structure into the aggression-promoting, sex-craving, risk-taking regulator with which we are all familiar. By the same token, the comparative lack of androgen hormones in the female produces the kinder, gentler, softer neural substrate that distinguishes itself from the male by dint of its vastly different behavioral repertoire.