Читать книгу Abnormal Psychology - William J. Ray - Страница 102

In a move to go beyond using only the signs and symptoms of psychopathology, there has been a search for stable internal physiological or psychological markers that underlie a disorder (Gottesman & Hanson, 2005; Gottesman & Shields, 1972; Insel & Cuthbert, 2009; G. Miller & Rockstroh, 2013). Such markers have been called endophenotypes. Endophenotypes are patterns of processes that lie between the gene (the genotype) and the manifestations of the gene in the external environment (the phenotype). Unlike symptoms that can be observed, endophenotypes cannot be seen except with special equipment and computational analysis such as brain imaging procedures or patterns of performance on neuropsychological tests. For example, individuals with a given disorder may show certain types of electroencephalogram (EEG) responses to particular stimuli or a certain pattern of brain activity that is different from that seen in healthy individuals. Those with autism have been shown to have fewer connections between brain areas than siblings or controls, and this is seen as an endophenotype (Moseley et al., 2015).

endophenotypes: patterns of processes that lie between the gene (the genotype) and the manifestations of the gene in the external environment (the phenotype)

Like genes, the presence of the endophenotype does not necessarily mean that the disorder itself will be present. For example, a specific endophenotype may be seen in both a person with schizophrenia and his or her first-degree relatives, although the relatives themselves do not have schizophrenia. As such, an endophenotype can help to identify the systems involved in a particular disorder as well as note which genes are influenced by environmental and other internal factors related to a disorder. The potential of endophenotypes is their ability to better articulate the relationship between genetic and environmental factors in the development of psychopathology and to clarify which processes are influenced. In Chapter 4, you will learn about a National Institute of Mental Health (NIMH)–supported diagnostic approach based on endophenotypes, the Research Domain Criteria (RDoC).

Concept Check

 What are the two important principles of Mendelian genetics? What evidence led Mendel to their discovery?

 What do genes do, and how and where do they do it? What are the roles of DNA and RNA in that process?

 How do we know that genes change behavior? What kinds of research have been done with animals to identify the specific genes involved?

 What is epigenetic inheritance? How does it work?

 What is an endophenotype, and how does it relate to psychopathology?