Schizophrenia, like cancer, is a commonly occurring disorder, denoted by a set of common characteristics. Its incidence per year is about 0.15 percent, and the lifetime probability for any individual to suffer a schizophrenic breakdown is about 1 to 2 percent.
There are approximately 600,000 schizophrenics in the United States (70,000 in Canada), and more than 200,000 Americans (20,000 Canadians) are presently hospitalized with some form of schizophrenia (Lehman, 1969). This disorder has been found in all parts of the world and in all populations studied.
In England, for example, 25 percent of all hospital beds in the National Health Service are occupied by individuals labeled as schizophrenic. Despite the prevalence of the diagnosis of schizophrenia, there is no condition over which there is more disagreement in the whole field of medicine. Every conceivable view is held by authoritative people, they stated, but, in general, theories about schizophrenia are based on either a psychosocial or a biological model.
The first scientific description of schizophrenia had its origins in the disease model, which gave way to a psychosocial emphasis in the Freudian era. With the advent of biochemical research and chemotherapy, the biological theories of schizophrenia have once more gained prominence. While still a controversial issue, the evidence derived from genetic studies of families, and particularly of monozygotic twins, suggest a hereditary basis for a number of psychiatric disorders and constitutes one of the strong arguments for the importance of biological factors in mental illness.
Children raised in separate environments have been found to have strikingly similar personalities. Scientific evidence for the biochemical theory of schizophrenia has steadily accumulated. Schizophrenic like symptoms have been produced through the ingestion of psychedelic drugs. Perhaps the most significant breakthrough for victims of schizophrenia was the introduction of chlorpromazine, a chemical which alleviates the symptoms and prevents the progress of this disorder.