Three Adoption Studies of Heredity in the Schizophrenic Disorders

Statistical Analysis in Genetic Studies of Mental Illnesses

Identifying the risk factors for mental illnesses is of significant public health importance. Diagnosis, stigma associated with mental illnesses, comorbidity, and complex etiologies, among others, make it very challenging to study mental disorders. Genetic studies of mental illnesses date back at least a century ago, beginning with descriptive studies based on Mendelian laws of inheritance. A variety of study designs including twin studies, family studies, linkage analysis, and more recently, genomewide association studies have been employed to study the genetics of mental illnesses, or complex diseases in general. In this paper, I will present the challenges and methods from a statistical perspective and focus on genetic association studies.

The genetic epidemiology of schizophrenia and the design of linkage studies

There are three aspects of schizophrenia that are challenges to the design of linkage studies. First, analysis of twin and family data have consistently failed to identify a single major gene effect. Second, ascertainment of multiplex families does not guarantee the sampling of families in whom a major gene is segregating even if such a gene exists. Third, environmental influences appear to play an essential role in the etiology of at least some schizophrenia. The implications of these features for linkage strategies in schizophrenia are discussed.

The attitudes of psychiatrists toward etiological theories of schizophrenia

This study is an analysis of psychiatrists' opinions on the etiology of schizophrenia. A random sample of members of the American Psychiatric Association uncovers a general hesitation on their part to subscribe to any particular etiological theory. Only four theories are viewed as causally related to schizophrenia: social isolation, cognitive breakdown, biochemical imbalance, and maternal deprivation. Attitudes toward etiological theories are significantly different among psychoanalysts, behaviorists, and eclectics. Attitudes also are related to the setting in which the psychiatrist practices.