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Chapter 2

Chapter 2

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University of Toronto Scarborough
Konstantine Zakzanis

ABNORMAL PSYCHOLOGY Chapter 2 Current Paradigms Paradigm: A set of assumptions, a general perspective, that defines how to conceptualize and study a subject, how to gather and interpret the data, even how to think of a particular subject Scientists work within different paradigms, which influence the way they approach topics, how they collect data, how they conduct experiments, and how they interpret data. Each paradigm has its own biases The Biological Paradigm (a.k.a medical modeldisease model) Is a continuation of the somatogenic point of view. It holds that mental illness is caused by dysfunctional biological processes. The biological paradigm was the dominant one for the majority of time psychopathology was studied. Most dominant between the late 1800s to mid 1900s Contemporary Approaches to the Biological Paradigm Behaviour Genetics Behaviour Genetics: The study of individual differences in behaviour that are attributed, in part, to differences in genetic makeup When a sperm and an egg come together, they form a zygote with 46 chromosomes, each with thousands of genes Genotype is the total genetic makeup of an individual (unobservable), whereas phenotype is the observable characteristics of an individual. Neither of these are fixed, unchanging entities; they change over time Note that many psychological disorders are not problems with the genotype, but rather the phenotype (phenotype = mix of the genetic makeup and environmental factors) Therefore it is incorrect to say that a psychological disorder can be directly inherited. Only the genotypic portion is inherited (through the genes of the parents). Whether or not the psychological disorder develops in the child depends on their life experiences and traumas Therefore a predisposition to develop a disorder is inherited, not the actual disorder itself. 4 methods are used to study the likelihood of inheriting a predisposition for a disorder: 1. Comparison of family members 2. Twin studies 3. Adoptee studies 4. Linkage studies a. Family Comparison www.notesolution.com Because the average number of genes shared between family members is known, it is possible to discover the level of inheritance by finding a relationship between the number of shared genes and the prevalence of a disorder in a family First a group of people with the mental illness being studied are gathered (called the probands or index cases). Then first degree relatives (parents, sisters, brothers. share 50% genetic makeup) are studied and second degree relatives (nieces & nephews. Share 25%). For a predisposition to be inherited, the first degree relatives should have the disorder at a higher rate than the general public. b. Twin Method Monozygotic and Dizygotic twins are compared to see if a disorder is concordant and therefore heritable If a disorder is found in both MZ twins (who share 100% of their genetic makeup) they are said to be concordant. For a predisposition to be heritable, the rate of concordance must be higher for MZ twins than DZ twins c. Adoptee Method Studies children adopted and reared away from their biological parents. The prevalence of the disorder in both parent and child are compared to those of parents living with their children. d. Linkage Analysis A method in molecular genetics where scientists compare the location of a known inherited trait a genetic marker - with the occurrence of a heavily concentrated disorder within a family. If the occurrence of the psychological disorder goes with the occurrence of the known trait (the genetic marker) it is assumed they are both on the same chromosome, on similar locations Scientists often hypothesize the gene-environment interactions in that they believe the development of a disorder has to do with genes + environment. Therefore if they find a link for a psychological disorder they hypothesize that the disorder will develop IF they come across the right environmental triggers It is difficult to interpret the data from this method because it is unknown what degree of the concordance has to do with the genetic predisposition inheritance and what degree has to do with the upbringing and experience Neuroscience & Biochemistry in the Nervous System Different neurotransmitters may cause different psychopathologies. I.e. too much norepinephrine may cause anxiety disorders, too much dopamine may cause schizophrenia, and too much serotonin may cause depression) Failure in the reuptake process may cause psychopathologies also (results in too much or too little www.notesolution.com
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