What is the theme in Johnny the Homicidal Maniac: Director's Cut by Jhonen Vasquez?

Depression is the primary theme throughout the novel as Johnny battles his own depression and self-loathing. Johnny's depression, in the beginning, appears to stem only from the treatment of others toward him. However, as the novel proceeds, it is clear Johnny's problems stem beyond such trivialities. Johnny's alter egos begin to explain that Johnny cannot remember his own past nor his current situation.