Mood symptoms are common in people with delusional disorders and often represent an emotional response commensurate with perceived delusional experiences. However, because mood disorders are common in the general population, they can present as comorbid conditions, often predating delusional disorders. The mood symptoms of mood disorders, unlike the mood symptoms of delusional disorder, are predominant and meet the criteria for a full mood episode (depressive, manic, or mixed). Delusions associated with mood disorders typically develop after the onset of mood symptoms and progress secondary to mood abnormalities. The mood symptoms of delusional disorder are usually mild, and delusions usually exist in the absence of mood abnormalities. Schizophrenia delusions are bizarre in nature and thematically associated hallucinations are common. Additionally, a disorganized thought process, speech, or behavior is present. Negative symptoms and functional deterioration are significant and cognitive deficits are common. The concept of delusional disorder has both a very short history, formally, but a very long history if we integrate the reports and observations of the last 150 years. The term delusional disorder was not coined until 1977. Manschreck (2000) used this term to describe an illness accompanied by persistent delusions and a stable course, distinct however from delusions that occur in other medical conditions and psychiatric. However, the concept of paranoia has been used for centuries. Originally, the word paranoia comes from the Greek para, meaning alongside, and nous, meaning mental intelligence (Munro, 1999). The Greeks used this term to describe any mental abnormality, in the same way we use the word madness. In the modern world, the term has reappeared...... middle of article...... Complete Handbook of Psychiatry: 1545-1550.Heinonen, H., Himanen, L., Isoniemi, H., Koponen, S., Portin, R., Taiminen, T. (2002). Axes 1 and 11 psychiatric disorders after head trauma: a 30-year follow-up study. Am J Psychiatry.159(8):1315-1321. (Medline).Lacan, J. (1993) Seminar 3: The Psychoses, 1955-56.Lacan, J. (1997, 2002) “On a question prior to any possible treatment of psychosis” in Ecrits.Lehmann, HE, & Ban, T. A. (1997). The history of the psychopharmacology of schizophrenia. Can J Psychiatry: 42: 152-62. [PubMed] Manschreck, T. C. (2000). Delusional and shared psychotic disorder. Delusional and shared psychotic disorder. Kaplan and Sadock's Complete Handbook of Psychiatry. (7th edition) pp. 1243-1264. Munro, A. (1999). Delusional disorder: paranoia and associated illnesses. Schreber, DP (1903) Memoirs of my nervous illness