The Behavioral Genetics of Psychopathology : a Clinical Guide by Kerry L. Jang pdf
This book explores the theories, etiology, measurement, diagnosis, and treatment of psychopathology from the perspective of behavioral genetics, a field of enquiry broadly concerned with the inheritance of emotional and behavioral patterns.
Why do clinicians need to know about the new findings being reported every day by behavioral geneticists? The aim of treatment is always to change emotional and behavioral patterns. An understanding of the genetic influences that contribute to behavioral variability and change helps practitioners and patients plan realistic goals and develop effective strategies to reach them.
For many people, the term behavioral genetics conjures up images of busy automated laboratories searching for susceptibility genes, a job known as genomics. With the mapping of the human genome, there is no doubt that genomics will continue to be a large part of what behavioral geneticists do. However, identifying the susceptibility genes is only one effort.
The real impact of behavioral genetics lies with studies that estimate the effect of identified or hitherto unidentified genes on behavior, a task that has been labeled behavioral genomics (Plomin & Crabbe, 2000). This book addresses the impact of behavioral genomics on how psychopathology is conceptualized and approached in our daily work.
Nurture depends on genes and genes need nurture.
This book is not just about genetics. In February 2001 it was announced that the human genome contains 30,000 genes, rather than the 100,000 originally expected. This startling revision led some to conclude that there are simply not enough genes to account for all the different ways people behave and that behavior must also be shaped by environmental factors. Behavioral geneticists are just as concerned with the influence of the environment and its interplay with genetic factors. This book will try to spend as much time examining the role of experience as biological factors on the development of mental illness.
Brain and nervous system disorders may cost the United States as much as $1.2 trillion annually, and affect many millions of Americans each year. Twin data suggest that more than 40% of the societal burden of brain disorders is likely to be genetically mediated. Most of this disease burden arises from complex multigene genetics as well as from environmental influences. The large sizes of these complex genetic burdens should encourage careful molecular and clinical work to link disease vulnerability variants with … prevention, diagnostics, and therapeutics.
—Uhl and Grow
An important purpose of this book is to begin the integration of genetics into clinical thinking and research. It is often thought that the only clinical application of genetic research is the development of drug therapies to counteract the offending gene’s product. The first major step in this process is to determine if the genes hypothesized to be associated with a disorder are actually present in patients with that disorder.
Once a gene is linked to a specific disorder, the biochemistry associated with the gene becomes the focus to determine the intracellular mechanisms by which abnormal behavior is produced. Many researchers in behavioral genetics are trained in medical genetics and other medical specialties. Their approach is to work from the bottom up: They take the fundamental unit of analysis to be the gene and its variants. Frustratingly, successes have been few and far between.
All is not lost, because a great deal of what behavioral geneticists do is to study the effects of these as-yet-to-be identified genes. They take a top down approach that begins with recognized disorders (e.g., the symptoms and signs of mental illness) and uses genetically informative samples, such as twins or adoptees, to determine if individual differences in the disorder are due to genetic variations or to changes in environmental conditions.
Genetic effects refer to the influence genes have on the development of individual differences in behavior relative to the influences of learning, experience, and environmental conditions. The size of genetic and environmental effects can be estimated for a single disorder such as major depression or for individual symptoms like sadness or insomnia.
We can estimate the relative genetic and environmental impact on virtually any behavior that can be measured reliably. This introductory chapter will explain some important basic concepts, such as the definition of illness, outline some of the criticisms leveled at behavioral genetic research, and finally describe some psychotherapeutic approaches being developed to address behavior whose expression may be fixed by inherited factors.