PSYB32H3 Chapter : ch.2 for PSYB32
19 Jul 2010
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Chapter 2
Twin Method: both monozygotic twins (identical; develop from a single fertilized egg; same sex) and dizygotic twins
(fraternal; develop from separate eggs and are on average only 50% alike genetically; can be same sex or opposite) are
compared
! Diagnosed cases compared to other twin to see presence of disorder
! When twins are similar diagnostically they are said to be concordant; concordance for disorder should be greater in
MZ pairs than DZ pairs! if this happens than disorder said to be heritable
! For child to get the disorder that the parents have, there doesn’t have to be a genetic predisposition it may run in
families only because of the environment the child was raised
! Equal environment assumption: environmental factors that are partial causes of concordance are equally influential for
MZ pairs and DZ pairs; assumption only applies to factors that are plausible environmental causes of
psychopathology; this assumption asserts that MZ pairs and DZ pairs have equivalent number of stressful life
experiences
! 3 factors as biasing heritability estimates: violation of the equal environments assumption, sex of the participants and
his or her age when the assessment took place
o Only environmental factors contributed to exposure to events involving non-assaultive traumas
o Both genetic and environmental factors contributed to exposure to assaultive traumas
o Therefore, genetic factors may determine the extent to which a person is likely to experience post-traumatic stress
after an assaultive trauma
Adoptees Method: study children who were adopted and reared apart of their parents with abnormal disorders
! If there is a high frequency of panic disorders found in children reared apart from parents who also had panic
disorders, then there would be support for the theory that genetic predisposition figures in the disorder
[Molecular Genetics]
! Tries to specify the particular gene or genes involves and the precise functions of these genes
! Each cell consists of 46 chromosomes with thousands of genes per chromosome (our genetic material)
! Allele: refers to any one of the several DNA coding that occupy the same position or location on a chromosome:
genotype is his or her set of alleles
! Genetic polymorphism: refers to variability among members of the species; involves differences in the DNA sequence
that can manifest in very different forms among members in the same habitat; entails mutations in a chromosome that
can be induced or naturally occurring
! Linkage analysis: method in molecular genetics that is used to study people; researches use it to study families in
which a disorder is heavily concentrated; they collect diagnostic info and blood samples from affected individuals and
their relatives and use the blood samples to study the inheritance pattern of characteristics whose genetics are fully
understood (genetic markers)
! If occurrence of a form of psychopathology among relatives goes along wit the occurrence of another characteristic
whose genetics are known, it is concluded that the gene predisposing individuals to the psychopathology is on the
same chromosome in a similar location on that chromosome (i.e. it is linked) as the gene controlling the other
characteristic
! Linkage analysis: mood disorders, OCD and schizophrenia
! Gene-environment interactions: notion that a disorder or related symptoms are joint product of a genetic vulnerability
and specific environmental experiences or conditions
[Neuroscience and Biochemistry in the nervous system]
! Neurons have 4 major parts: cell body, several dendrites (short and think extensions), one or more axons of varying
lengths (usually only one long and thin axon extending considerable distance from the cell body) and a terminal
buttons on the many end braches of the axon
! Nerve impulse: change in electric potential of the cell
o When neuron is stimulated at its cell body or dendrites a nerve impulse travels down the axon to the terminal ending.
Between the terminal ending and cell membrane of receiving neuron is a small gap called the synapse
o Terminal buton of each axon contains synaptic vesicles (small structures that allow a nerve NT); NT are chemical
substances that allow a nerve impulse to cross the synapse
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o Nerve impulses cause the synaptic vesicles to release molecules of their transmitter substances and these molecules
flood the synapse and diffuse toward the receiving or postsynaptic neuron cell membrane of the postsynaptic cell
contains proteins (receptor sites) that are configured so that specific NT can fit into them when NT fit into receptor
site a msg can be sent to postsynaptic cell
o What happens to postsynaptic neuron depends on its integrating thousands of similar msgs
" Sometimes msgs are excitatory: leading to the creation of nerve impulse in the postsynaptic cell
" Msgs is inhibitory: making postsynaptic less likely to fire nerve impulse
! Returning back to normal state:
o Not all released NT has found its way to postsynaptic receptors- some broken down by enzymes and some pumped
back into the presynaptic cell through a process of reuptake
! Norepinephrine: NT of the peripheral sympathetic nervous system is involved in producing states of high arousal and
therefore may be involved in anxiety disorders
! Serotonin and dopamine are NT in the brain; serotonin involved in depression and dopamine in schizophrenia
! GABA: inhibits some nerve impulses and may be involved in anxiety disorders
! Maturational changes influence NT levels
o Onset of puberty results in decrease in serotonin and a decrease in dopamine activity in certain cortical areas
! Disorder is caused y either too much or too little of a particular transmitter (i.e. mania- too much norepinephrine;
anxiety disorder- too little GABA)
! Synthesis of NT (series of metabolic steps): amino acids! enzymes catalyzes each reaction
o Too much or little of NT results form error in one of the metabolic pathways or from alterations in usual processes
by which transmitters deactivated after being released into the synapse (i.e. reuptake)
" Failure to pump leftover NT back into presynaptic cell and then new nerve impulse causes further NT to be
released into synapse therefore postsynaptic cell has double the dose of NT therefore more likely to fire a
nerve impulse
! Receptors are also a cause of psychopathologies
o If receptor on postsynaptic neuron were too numerous or too easily excited the result would be akin to having too
much transmitter released therefore more sites available with which the NT could interact, increasing the changes of
the postsynaptic neuron would be stimulated
" Delusions and hallucinations of schizophrenia may result from an over abundance of dopamine receptors
[Biological Approaches to Treatment]
! Prevention or treatment of mental disorders should be possible by altering bodily functioning; biological defect #
biological intervention
! Use of Psychoactive drugs increasing;
o tranquilizers (valium) effective in reducing tension associated with some anxiety disorders by stimulating GABA
neurons to inhibit other neural systems that create the physical symptoms of anxiety
o antidepressants (Prozac) increase neural transmission in neurons that use serotonin as a NT by inhibiting reuptake of
serotonin
o antipsychotic drug (Clozaril) used for treatment of schizophrenia; reduces the activity of neurons that use dopamine
as NT by blocking their receptors
o stimulants (Ritalin) used to treat children with attention deficit and hyperactivity disorder; these increase levels of
several NT that help children pay attention
! drugs can act efficiently and often provide symptomatic improvement relatively quickly
o serotonin reuptake inhibitors described as having delayed onset; helps to treat depression
! contemporary approaches to biological assessment: involves attempts to make inferences about the functioning of the
nervous system (neuropsychological assessment) or to “see’ the actual structure and functioning of the brain and other
parts of the nervous system (MRI)
! clinical scientist can believe in biological basis of mental problem but can recommend psychological intervention
! effects of cognitive-behavioural theory (CBT) on OCD showed decreased metabolism in the right caudate nucleus
whereas, CBT in phobia resulted in decreased activity in limbic and paralimbic areas
! different effects for different types of interventions
[Evaluating the Biological Paradigm]
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! reductionism: view that whatever is being studied can and should be reduced to its more basic elements or
constituents
! problems such as delusional beliefs and dysfunctional attitude may well be impossible to explain biologically, even
with detailed understanding of the behaviour of individual neurons
PSYCHOANALYTIC/PSYCHODYNAMIC PARADGM
! developed by Sigmund Freud! psychopathology results from unconscious conflicts in the individual
[Classical psychoanalytic theory] !refers to original views of Freud; his theories encompassed both the structure of the
mind itself and the development and dynamics of personality
-Structure of the mind-
! he divided the mind into 3 parts : id, ego and superego- metaphors for specific functions or energies
! id: present at birth and is part of the mind that accounts for al the energy needed to run the psyche
o comprises basic urges for food, water, elimination, warmth, affection and sex
o source of all id’s energy is biological
o as infant develops: energy called libido, converted into psychic energy, al of it unconscious, below the level of
awareness
o id seeks immediate gratification and operates according to the pleasure principle
o when id not satisfied, tension produced and it strives to eliminate the tension
o to obtain gratification: primary process thinking: generating images-fantasies- of what is desired
! Ego: conscious and begins to develop from the id during the second six months of life; its task is to deal with reality
o Thru its planning and decision-making functions, called secondary process thinking, ego realizes that operating on
the pleasure principle at all times is not the most effective way of maintaining life
o Ego operates on the reality principle as it mediates between the demands of reality and immediate gratification
desired by the id
o Primarily conscious and involved in thinking and planning, it has important unconscious aspects (defence
mechanisms) that protect it from anxiety
! Superego: operates roughly as the conscience and develops throughout childhood
o Develops from ego much as the ego developed from the id
o As children discover that many of their impulses are not acceptable by their parents they begin to incorporate or
introject, parental values as their own to enjoy parental approval and avoid disapproval’
! Interplay of forces referred to as psychodynamics of the personality
! Freud postulated that much of human behaviour is determined by forces inaccessible to awareness
! Id’s instinct and many of superego’s activities are not known to the conscious mind
! Freud considered most of the important determinants of behaviour to be unconscious
-Neurotic Anxiety-
! When one’s life is in jeopardy, one feels objective (realistic) anxiety- ego’s reaction to danger in the external world
! Neurotic anxiety: feeling of fear that is not connected to reality or to any real threat: a person who has fixated at one
or another stage during development in personality may experience this
! Moral anxiety arises when impulses of the superego punish an individual for not meeting expectations and thereby
satisfying ht principle that drives the superego- perfection principle
-Defence Mechanisms: coping with anxiety-
! Objective anxiety can be reduced by: removing or avoiding the danger in the external world or by dealing with it in a
rational way
! Neurotic anxiety can be reduced by means of defence mechanisms: strategy unconsciously used to protect ego from
anxiety
o Repression: pushes unacceptable impulses and thought into the unconscious; by remaining repressed infantile
memories and desires cannot be corrected by adult experience and therefore retain their original intensity and
immaturity
o Denial: disavowing a traumatic experience and pushing it into unconscious
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