Your brain on depression~ PET scan shows hot spots of increased activity in the brain of a non-depressed person. (Depression is not a sign of weakness or negative personality. It is a major health problem and a treatable medical condition)
Normally, cortisol helps us fight back and cope with pressure. However, if you were to engage in intense depressive thinking for a period of 3 to 4 weeks, there is a likelihood that the level of cortisol within your blood stream will become way too much.
10 Ways to Show Love to Someone With Depression - Very good article to help others understand how to love their partner, friend, family member when they are suffering from significant depression. This is the best article that I've read.