What women want: Science remains baffled

"Those wily women with eyes 'false in rolling', who change their moods and affections like chameleons."  Sonnet 20, William Shakespeare

400 years ago when the brilliant Shakespeare first penned this keen observation, commenting on the ever-changing nature of a woman's spirit, the knowledge that a woman's emotions could fluctuate with her hormones was unknown.  The first hormone would not be discovered for another 300 years, and shortly after - the components of the menstrual cycle would be elucidated. Given the rapid advancement of science in the twenty first century and the ease with which peering into the brain has become; one would think the influence of the sex hormones estrogen and progesterone on cortical and subcortical regions implicated in a woman's emotional and cognitive processes would be fully understood.  Not so. 

In a recent review in the Journal of Psychoneuroendocrinology, brave authors gathered all that science could currently tell us regarding the function of hormones in the female brain.  While investigations included women undergoing experimental manipulations such as hormonal treatments for gender dysphoria, I will only focus on naturally cycling women (NCW) and those on oral contraceptives (COC).

High hormonal status was defined for estrogen (E2) as late follicular or COC use, while for progesterone (P4) late luteal for NCW or COC use.  Low hormonal status was defined as early follicular for E2, follicular for P4 or non-COC use.

Image credit here.

Effects on Emotion.

In naturally cycling women

Multiple studies found an enhanced response in the orbital frontal cortex (OFC) to negative pictures the early follicular phase. Even more interestingly, activity in this area was stimulated only by male faces.   Before menstruation, in the mid-luteal phase, the anticipatory response to erotic pictures in the anterior cingulate cortex (ACC) was enhanced.  While the hippocampus (a region responsible for encoding memories) showed a decrease in activation for positive stimuli when estrogen levels were high, the opposite became true when estrogen levels dropped. 

So before she menstruates, a woman is angrier at males, yet feels aroused, all while crying uncontrollably at the Budweiser Clydesdale Puppy commercial. Nothing new.

In women on birth control

By far the most interesting finding is that only after three weeks on birth control, amgydala (emotions) response was larger, diminished activation of the inferior temporal gyrus (memory), and an overall different pattern of brain activity as compared to NCW. Activity in areas responsible for processing of erotic pictures was highly increased as compared to NCW.  Birth control also had the ability to reduce the activity of the right fusiform gyrus (face recognition) and left amygdala while encoding emotional faces.

Women on birth control employ different areas of the brain, are less emotionally reactive, more sexually aroused and the data suggests - unskilled at interpreting feelings on other’s faces. That's new.

Effects on Cognition.

In naturally cycling women

High levels of hormones were associated with reduced functional interhemispheric connectivity as well as prefrontal connectivity. In other words, the two hemispheres of the brain are not communicating well: thinking is cloudy and ideas don’t flow.

In women on birth control

 While midbrain structures (ACC) were activated in number processing tasks, several fronto-parietal clusters were deactivated.  Simply put, the brain is adjusting for the high flood of hormones and using different structures to complete the cognition task.

The theory behind the vast difference in behavior between the two sets of women rests in the neurotransmitter systems hormones they likely influence. Serotonin and dopamine are crucial for physiological regulation of mood, learning, memory and cognitive flexibility.

When investigating emotional or cognitive tasks in the brain, it's vitally important to take into account the influence of sex steroid hormones on these processes. 

Unfortunately, the investigation on the complex genetic interplay of hormones and neurotransmitters is still in its infancy and the answers to these questions will have to wait. In addition, there is a large selection of birth control options, which further muddles the analysis. 

Almost a half century later from Shakespeare’s time, neuroscience research still hasn’t untangled the chameleon-like semblance of a woman’s mood. The field has barely scratched the surface, and is currently peppered with phrases such as “largely unknown,” and “heterogeneous findings.” The “juvenile” field urgently needs to find real answers with applicable solutions to neuropsychiatric disorders.

The research did, however, debunk the myth that prior to menstruation, women think like men due to their estrogen levels being low and their brains being more “male-like.”  

ResearchBlogging.org Toffoletto, S., Lanzenberger, R., Gingnell, M., Sundström-Poromaa, I., & Comasco, E. (2014). Emotional and cognitive functional imaging of estrogen and progesterone effects in the female human brain: A systematic review Psychoneuroendocrinology, 50, 28-52 DOI: 10.1016/j.psyneuen.2014.07.025