Mood symptoms are common in people with delusional disorder and often represent an emotional response commensurate with perceived delusional experiences. However, because mood disorders are common in the general population, they may present as comorbid conditions, often preceding delusional disorder. The mood symptoms of mood disorders in contrast to the mood symptoms of delusional disorder are prominent and meet the criteria for a full mood episode (depressive, manic, or mixed). Delusions associated with mood disorders usually 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. The delusions of schizophrenia are bizarre in nature, and associated thematic hallucinations are common. Additionally, there is disorganized thought process, speech, or behavior. Negative symptoms and deterioration of function are prominent, and cognitive deficits are common. The concept of delusional disorder has a very short history, formally, but a very long history if you integrate reports and observations over the last 150 years. The term delusional disorder was coined only in 1977. Manschreck (2000) used this term to describe an illness with persistent delusions and a stable course, but separate from delusions that occur in other medical and psychiatric conditions. However, the concept of paranoia has been used for centuries. Originally the word paranoia comes from the Greek para, meaning beside, and nous, meaning intelligence of the mind (Munro, 1999). The Greeks used this term to describe any mental abnormality similar to how we use the word insanity. In the modern world, the term has reappeared... in the middle of the paper... Comprehensive Textbool of Psychiatry: 1545-1550.Heinonen, H., Himanen, L., Isoniemi, H., Koponen, S., Portin, R ., Taiminen, T. (2002). Axis 1 and 11 psychiatric disorders after traumatic brain injury: 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 preliminary question 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. Complete textbook of psychiatry by Kaplan and Sadock. (7th edition) pp. 1243-1264. Munro, A. (1999). Delusional disorder: paranoia and related illnesses. Schreber, DP (1903) Memoirs of my nervous illness