Progesterone Levels Linked to Different Emotion-Control Brain Patterns

Researchers at the University of Barcelona examined whether two ovarian hormones, progesterone and estradiol, were linked to brain activity involved in emotion control. Emotion control means adjusting an automatic reaction when a situation calls for something different.

The study included 116 healthy young women who were naturally cycling, meaning they were not using hormonal contraception. Each participant gave a saliva sample so the researchers could measure estradiol and progesterone. They also answered questions about mood and menstrual-cycle stage.

During a functional MRI scan, participants completed an approach-avoidance task using happy and angry faces. In some trials, they followed the more automatic response: approaching a happy face or avoiding an angry face. In other trials, they had to do the opposite: avoid a happy face or approach an angry face.

The opposite-response trials were designed to require more control over an automatic emotional tendency. Participants were slower and less accurate on those harder trials, according to the study abstract.

The researchers used a type of computer analysis called multivoxel pattern analysis. Rather than looking only at the overall activity of one brain area, this method examines patterns across many small parts of the scan. The team tested whether these patterns could distinguish between the task conditions.

The analysis could reliably tell apart task conditions from activity patterns in several brain regions. These included the lateral frontal pole, a part of the frontal brain region, and the striatum, which is involved in several functions including action and reward processing. Other regions also showed distinguishable task patterns.

Progesterone was the hormone tied to the main result. Higher progesterone levels were associated with lower accuracy for distinguishing task conditions from activity patterns in the lateral frontal pole and striatum. In plain language, the brain patterns for the different emotion-action situations looked more alike when progesterone levels were higher.

The statistical links were modest. The correlation between progesterone and classification accuracy was minus 0.26 in both the lateral frontal pole and striatum. A negative correlation means that, in this study, higher progesterone levels tended to occur alongside lower ability of the computer analysis to separate the task conditions.

Lower distinguishability in the lateral frontal pole was also linked with poorer self-reported mood during the preceding week. That association had a correlation of minus 0.25. The researchers reported that this brain measure accounted for 7.1% of the indirect association between progesterone and worse mood.

These results point to a possible explanation for how normal hormone changes may relate to mood variation: progesterone may be associated with changes in how the brain represents emotionally challenging actions. Still, this is an association, not proof of cause and effect. The study measured hormones, brain activity and mood at one point in time, so it cannot establish whether progesterone led to the brain-pattern differences, whether another factor affected both, or whether the relationship works differently over time.

The abstract says the study examined both estradiol and progesterone, but it reports no estradiol-specific findings. It also studied healthy young women who were naturally cycling, so the findings may not apply to people using hormonal contraception or to other groups.

Further research would need to follow people across menstrual cycles and test whether these scan patterns are consistently related to mood changes or emotion control outside the MRI setting.