DW: Mr. Fiedler, is it possible that someone could use a weapon against others because they are "depressed"?

Georg Fiedler: First I would like to clarify that the term "signs of depression" describes how someone appears to others. I would say that the police were very cautious in describing the perpetrator. "Signs of depression" in no way suggests that someone suffers a psychiatric illness. And even if they do, someone who suffers from depression is generally not someone who goes on a shooting rampage. People who are depressed direct their aggression against themselves, if anyone. Therefore one cannot assume that depression was the reason or cause of the attack.

How prevalent is depression in Germany?

Psychologist Georg Fiedler cautions against coming to hasty conclusions

About a third of the people living here show "signs of depression." But depression is a very broad term. It can suggest that someone lives reclusively, broods a lot, blames oneself or thinks their problems are somehow their own fault. There are a lot of things that play into the equation. Yet these character traits in no way mean that the person is sick. "Depression" is a term that is used in a rather inflationary sense here. Real depression is a very serious illness. Depression consists of symptoms such as constant serious brooding, waking up early and sleeplessness over a period of weeks or months.

The perpetrator was an 18-year-old German-Iranian. What could push a young person like him to commit such a horrible act?

One has to be careful in judging such a case. One thing is clear: There were a number of reasons for the crime. Apparently the perpetrator was undergoing psychiatric treatment. Therefore psychiatric illness could have played a role, but it was certainly not the only factor. Computer games that glorify violence, and are so popular with today's youth, are always pointed to after such atrocities. But the fact that the perpetrator liked to play so-called "ego-shooter" games cannot be the sole reason for this outburst of violence. People that draw that conclusion are oversimplifying. The reasons for such acts are much more complex than that.

The term "extended suicide" was used in reference to the perpetrator. What does that term mean?

The term refers to the fact that a perpetrator takes the lives of people close to them when they commit suicide. That can refer to a mother that kills herself and her child, or a father that kills himself and his entire family. In both cases the perpetrator exhibits a delusional notion that his or her victims could not possibly survive without them. Thus, one could even speak of altruistic motives in such cases. But that was absolutely not the case in Munich.

Does the Munich attack remind you of other cases?

Here too: The intentional crash of the Germanwings plane last March was certainly not exclusively related to the pilot's depression. I would think that he also had problematic personality traits. One of those traits would be a "delusional" perception of the world around him. If we think back a few years, the Winnenden shooter was also being treated for depression. But again: There were a whole series of factors that led to the attack, none of which had anything to do with depression. A psychiatric diagnosis of depression would actually speak against such an act.

Do you see correlations between the two attacks?

I found it rather telling that the Munich shooter seemed to pick out and shoot young people. In that sense the victims that were targeted were very similar to those targeted in Winnenden. It also brings to mind the Norway massacre that took place five years ago, in which a gunman killed 77 people, the great majority of whom were very young.

This interview was conducted by Daniel Heinrich.

Georg Friedrich is a psychologist and suicide researcher who lives and works in Hamburg, Germany.