I think this song is about Iran or Iraq actually. When he is talking about the antidepressants controlling tools of your system, I think he's having a go at consumerist culture and pr or Propaganda(corporate propaganda), as a means of making us feel happy, and entertaining us all the time, in order to preoccupy us and distort the truth. For me he's using antidepressants controlling our biogical systems, and our minds and moods, as a metaphor for of corporations and the media manipulate our thoughts and keep us happy. Serj is using anti-depressants as a symbol as they are common in our society as a quick fix to keep or make people happy, or less sad. Because of all the alienation they are feeling because consumerism isn't fulfilling their needs, and is making them sick.