Schizophrenic disorders are more severe in nature than other types of psychological disorders. Disturbing thoughts and perceptions, inappropriate behavior and emotion, and social withdrawal plagues individuals with schizophrenic disorders. Major categories of schizophrenic disorders include catatonic, paranoid, undifferentiated, and disorganized. With disorganized schizophrenia, the individual has hallucinations and delusions, while a person with catatonic schizophrenia displays bizarre motor behavior. People suffering from paranoid schizophrenia experience delusions of grandeur, persecution, or reference in which they completely misinterpret events. People with undifferentiated schizophrenia have hallucinations, delusions and incoherence. Causes of schizophrenia include genetic factors and neurobiological factors.
Of the many categories mental disorder recognized by psychologists and psychiatrists, schizophrenic disorders are perhaps the most potentially devastating of all. Sometimes referred to as the Cadillac of mental disorders, schizophrenia in its most severe form can negatively impact a variety of abilities and processes that define us as human beings. Though the term itself translates as "split mind," schizophrenia is not multiple personality or dissociative disorder, as many lay people are prone to believe. According to Holmes, schizophrenia is "a set of serious disorders that involve a decline in functioning, along with such symptoms as hallucinations, delusions, and/or disturbed thought processes, which must persist for at least six months". Each of these issues will be discussed in this paper, along with theories related to the causes of schizophrenia.
According to the Diagnostic and Statistical Manual of Mental Disorders IV TR, a person diagnosed with schizophrenia must have previously manifested normal or near-normal functioning before the decline mentioned in Holmes' definition above. Each individual is unique, of course, and retrospective perspectives by family members might certainly suggest that a person currently diagnosed has always been a bit "different." However, such statements are undoubtedly colored by what they have witnessed in their loved one as she or he began to manifest symptoms of the disease. In any case, regression from former level of functioning is one of the criteria for schizophrenia.