The unipolar-bipolar depressive dichotomy and the relationship between afternoon prolactin and cortisol levels

Afternoon prolactin and cortisol levels were measured in 29 patients suffering from a current major depressive episode. Among the 15 unipolar depressed patients the afternoon prolactin and cortisol levels were positively correlated, but 14 bipolar depressed patients did not show a similar relationship, and had prolactin levels lower than the unipolar patients. This finding adds to the growing list of ways in which the neurobiology of bipolar and unipolar depression may differ.