How do sex hormones shape our brain and behavior?

Our sense of well-being is linked to our hormones. Nearly twice as many women as men develop depressive illness. While this suggests that sex hormones play a key role in depression, it is not understood how they affect mood. Very little is known about how the brain is influenced by endogenous hormonal changes across the range of days to months. This is a critical gap, because many mental illnesses show large fluctuations over this timescale. Recent evidence suggests short-term changes in neurochemistry and functional and structural networks modulated by physiological sex-hormone fluctuation.