Q: I’m confused on the melancholia concept. You said that melancholia and mixed depression are more episodic and severe, but then you described melancholia as a component of unipolar depression, identified as chronic involutional melancholia. What is the difference between melancholia as part of manic-depressive illness (MDI) and unipolar?

Also, is bipolar depression as a psychomotor retardation illness a melancholic presentation?

PL: The question is misstated because DSM concepts remain so strong. MDI means bipolar illness plus unipolar depression. Unipolar depression does not mean non-bipolar depression, because there are other depressive conditions that are neither unipolar nor bipolar, meaning they are not part of MDI. MDI is a disease of severe mood episodes that being early in life. Another depression is mild and chronic (not severe and episodic), called neurotic depression. Another depression is severe and chronic and late in age of onset, called in the past “involutional melancholia.” That’s the difference between melancholia as part of bipolar or unipolar depression (MDI), and involutional melancholia. Melancholia as part of MDI is episodic – it has episodes that come and go and last about 3-6 months. Melancholia as part of chronic involutional melancholia is chronic – it has no end; once it begins later in life, it is present all the time. So the difference is in the course, not the symptoms.

“Bipolar depression” is as false as “major depressive disorder”: it has no meaning by itself, but rather consists of melancholic depressive episodes, or mixed depressive episodes, or pure depressive episodes. So it is melancholia if it meets melancholia definitions, which includes but is not limited solely to psychomotor retardation (also anhedonia and lack of mood reactivity).