Women who take the Pill may be getting more than protection against pregnancy. A new study indicates that this popular form of contraception can also increase brain size, including the areas associated with memory and social skills.
Brain size differences in men and women
When it comes to brain size, research indicates there is a difference between males and females in specific areas of the brain. Generally, males have a larger amygdala (memory and emotions) and hypothalamus (metabolic processes), while females have a larger caudate (memory and learning) and hippocampus (long-term memory and spatial navigation). Overall, women have a greater percentage of gray matter, while men have a higher percentage of white matter and cerebrospinal fluid.
The new study, which appears in the journal Brain Research, is the first to evaluate the impact of hormonal contraceptives on brain structure. Participants included 28 women, half of whom were taking the Pill, and 14 men. Scientists took high-resolution images of the subjects’ brains and compared the results.
The women who were not taking the contraceptive were scanned more than once to account for fluctuations in hormone levels that normally occur. Overall, the investigators found that women who took the Pill showed an increase in brain size of about 3 percent. This increase was the same regardless of which formulation of the contraceptive the women took.
According to Belinda Pletzer of Salzburg University, the hormones in the Pill clearly had a “tremendous effect” on the brains of the women. The increase in brain size was observed in regions already known to be larger in women when compared with men. Pletzer noted that “Larger volumes of a brain area could lead to an improvement of the functions this area is responsible for.”
For women who take the Pill, therefore, this could mean an improvement in memory and verbal and social skills. Pletzer also noted that any behavioral changes in the women associated with use of the Pill “are likely to affect those skills that are already better developed in women compared to men like, for example, memory.”
Why does the Pill seem to make parts of a woman’s brain larger? One theory is that the hormones in the contraceptive somehow strengthen the links between the nerve cells in the brain.
The Pill did not appear to have an impact on brain areas that are larger in men. It also did not cause an increase in the overall size of the brain. For now, investigators do not know whether the parts of the brain that showed an increase will shrink back to their original size when women stop taking the Pill or what impact, if any, stopping will have on memory and verbal skills.
Daily Mail, August 19, 2010
Pletzer B et al. Brain Research 2010 Aug 12; 1348:55-62