The world of psychiatry started from the medical concern of “psyche” – the mind, soul, or spirit in its Greek roots. The only syndrome in psychiatry that remains a linguistic link to psyche, psychosis is one of the most intriguing phenomena of human mind, the most impairing mental deficiencies, and the primary topic of psychiatric research.

The clinical features of psychosis are centered in the impairment of reality test. Psychotic symptoms include disorganized thought, disturbing behavior, and, most memorably, the formation of hallucinations and delusions, which are often peculiar and bizarre.

The DSM-IV-TR allows nine diagnoses of psychotic disorders

1. ▶ Schizophrenia

2. ▶ Schizophreniform disorder

3. ▶ Schizoaffective disorder

4. ▶ Delusional disorder

5. ▶ Brief psychotic disorder

6. ▶ Shared psychotic disorder

7. ▶ Psychotic disorder due to general medical condition

8. ▶ Substance-induced psychotic disorder

9. ▶ Psychotic disorder not otherwise specified (NOS)

The diagnosis of psychosis relies on clinical assessment and exclusion of general medical conditions that may also cause psychotic symptoms. Neurological abnormalities have been reported, primarily in limbic system, basal ganglia, and thalamus; however, these changes are not significant enough to have diagnostic value. Schizophrenia is considered by many the prototype of psychotic disorders, and is subjected to extensive research. The etiology of schizophrenia is not yet completely unveiled. Accumulated evidence traces down the contributing factors of both genetic and environmental nature. Regarding the nature of the process of the disease, there seems to be more evidence to support the assumption of neurodegenerative than neurodevelopmental. Schizophrenia may also be the manifestation of more than one disease process.