Irving Kirsch — American Educator born on March 07, 1943,

Irving Kirsch is Associate Director of the Program in Placebo Studies and a lecturer in medicine at the Harvard Medical School and Beth Israel Deaconess Medical Center. He is also professor emeritus of psychology at the Universities of Hull and Plymouth in the United Kingdom, and the University of Connecticut in the United States. Kirsch is noted for his research on placebo effects, antidepressants, expectancy, and hypnosis. He is the originator of response expectancy theory, and his analyses of clinical trials of antidepressants have influenced official treatment guidelines in the United Kingdom. He is the author of the 2009 book, The Emperor's New Drugs... (wikipedia)

Nocebos often cause a physical effect, but it's not a physically produced effect. What's the cause? In many cases, it's an unanswered question.
There are a variety of techniques to help people change the kind of thinking that leads them to become depressed. These techniques are called cognitive behavioral therapy.
There seem to be many causes of depression. One cause is profound loss, grief. Economic hardship we know is linked to depression. We don't have a full picture.
Psychotherapy works, and some types of therapy have been shown to be much more effective than antidepressants over the long run.
Anything that instills a sense of hope will at least temporarily help treat depression.