Oct. 25, 2005 -- Whether or not a woman suffers from monthly premenstrual mood swings may be related to how her brain is wired as well as her hormones.
A new study shows that women who experience no menstrual mood changes use parts of their brain differently than women who have PMS (premenstrual syndrome), a condition marked by mood swings prior to menstruation in addition to other symptoms.
Researchers found women with steady moods had heightened activity in parts of their brain thought to control emotions. They say this increased activity may make them less susceptible to the emotional effects of hormonal changes associated with the menstrual cycle.
Brain Plays a Role in Premenstrual Mood Swings
In the study, researchers examined brain scans of 12 women without premenstrual mood symptoms. The brain scans were taken one to five days before the first day of their period (premenstrual) and eight to 10 days after menstruation (postmenstrual).
During each brain scan, the women saw printed words with 80 positive, 80 negative, and 80 neutral connotations, such as "safe," "death," or "bookcase," while performing other tasks.
The results showed that the women had greater activity in the medial regions of the orbitofrontal cortex of the brain during the premenstrual period and increased activity in lateral regions of this area after menstruation.
The orbitofrontal cortex has been linked to emotions, motivation, and decision making, according to the researchers.
Researchers say the changes seen on the brain scans were not reflected in the women's apparent emotional state. Therefore, they suspect that this increased activity in the separate areas of the orbitofrontal cortex influences the ability for women to compensate for the hormonal changes while maintaining a consistent emotional state.
The results appear in the Proceedings of the National Academy of Sciences.