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.

Men can more callously steel their hearts against mood swings than can women.

Mood disorders including unipolar & bipolar depression & generalized anxiety disorder are exquisitely sensitive to sexual, thyroidal & adrenal hormones.