MRI links progesterone to blurred emotion-control signals in women

The screen inside the MRI showed two faces: happy or angry. The 116 participants had to approach the happy face and avoid the angry one—or do the opposite. In that controlled moment, researchers from the University of Barcelona found that higher progesterone levels were linked to less distinct brain-activity patterns for the easier and harder versions of emotion control.

Emotion control is the ability to override an automatic response when a situation demands it. A machine-learning analysis of the scans could identify whether a participant was facing the easy or difficult version of the task. But when progesterone was higher, activity patterns in the lateral frontal pole were more alike, suggesting that the brain was less able to distinguish between the two emotional demands.

The distinction also tracked mood. Participants whose scans showed a clearer separation between easy and difficult situations tended to report better mood during the preceding week. The brain mechanism accounted for roughly 7% of the variation in mood scores. The researchers measured naturally occurring ovarian hormones through saliva rather than testing a progesterone treatment.

And so, concretely, the finding could eventually help clinicians assess why some women are more sensitive to hormone-related mood changes and tailor care for problems such as premenstrual dysphoria. Professor Ulrike Krämer of the University of Lübeck, who was not involved in the study, said the results may also help women understand recurring changes in mood and behavior as shifts in brain chemistry rather than a personal failing.

The evidence remains an association, not a causal explanation. Lead author Macià Buades-Rotger said a one-time measurement could not establish whether progesterone produces the change. The study found no equivalent signal for estradiol, but author Rosamunde Hendricks said that hormone may be harder to measure accurately in saliva. Future research will also need to test whether the same link exists in men.