I remember some years ago looking up the definition of major depressive disorder (MDD).  The book described major depression as a "psychiatric disorder" characterized by a set of typical symptoms, which it went on to describe in some detail.

Estrogen makes women saner, less belligerent & destructive than men, & it protects then in a natural way against psychosis, including schizophrenia, as well as ADHD, autism and OCD.