The causes of the major psychiatric disorders such as schizophrenia, manic depressive illness, and the dementias of senility still elude us despite burgeoning research in the neural and behavioral sciences over the past few decades. Equally obscure are the roots of serious behavioral disturbances such as suicide, sociopathy, and substance abuse. All of these are tragic, all costly to the individual, to the family, and to society. These problems are found among all races and nations, and in many societies account for a major fraction of the costs of health care and the loss of human potential. It is there that schizophrenia is the most serious of the mental disorders.

Genetic factors in the etiology of schizophrenia

The well-known observation that the major psychoses, schizophrenia and manic-depressive illness, tend to show a familial distribution has led many investigators to assume the importance of hereditary factors in their etiology. Although others have attempted to explain that phenomenon in terms of familial rearing and acculturation, the role of heredity has been reinforced, not only by studies on twins but by recent studies employing adoption to separate the genetic and environmental influences. In addition, the latter studies have opened the way to new research aimed at the identity of etiologically important genes. Molecular genetic techniques are being used, without notable success to date, in a search for linkage between given mental disorders and chromosomal regions in pedigrees with multiple instances of the disorder.