I haven't read the book, but it sounds like a very simplistic view of depression.
As others have said, there are several types, some in my own family.
I don't think bipolar - or manic depression - has been mentioned.
Or a type of depression in old age which could be chemically based (an aunt and an old male friend had this.)
Briefing against women ministers in Westminster
Walking sticks in "tottery" in old age
What’s a household item that reminds you of your grandma’s house?


