Enzo - The term I see most frequently used in English is MI for Mental Illness (at least, among the general public). Language can sometimes be problematic, as we are an international community. :))
Now, do you know about cognitive dissonance? A short primer can be found here: http://www.simplypsychology.org/cognitive-dissonance.html
Here's the intro, and how Festinger first got thinking about CD -- surprise, a CULT!
Cognitive dissonance refers to a situation involving conflicting attitudes, beliefs or behaviors.
This produces a feeling of discomfort leading to an alteration in one of the attitudes, beliefs or behaviors to reduce the discomfort and restore balance etc.
For example, when people smoke (behavior) and they know that smoking causes cancer (cognition).
Festinger's (1957) cognitive dissonance theory suggests that we have an inner drive to hold all our attitudes and beliefs in harmony and avoid disharmony (or dissonance).
...
Cognitive dissonance was first investigated by Leon Festinger, arising out of a participant observation study of a cult which believed that the earth was going to be destroyed by a flood, and what happened to its members — particularly the really committed ones who had given up their homes and jobs to work for the cult — when the flood did not happen.
While fringe members were more inclined to recognize that they had made fools of themselves and to "put it down to experience", committed members were more likely to re-interpret the evidence to show that they were right all along (the earth was not destroyed because of the faithfulness of the cult members).
Okay, if a cult member is experiencing cognitive dissonance, they are open to depression in a big way. Their logic is constantly at odds with their feelings. They see reality, but their religion, their very way of life, denies it. This is mental illness. This leads to depression.
On a personal anecdotal note, I can remember my mother telling me, through the 90s and early 00s, about how this sister and that one, is on Prozac or some other SSRI. She herself has been taking anti-depressants for years.
The happiest people on earth? I think not.
tal