PSYC 1000 Chapter Notes -Dopamine Receptor, Positron Emission Tomography, Thought Disorder

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Published on 6 Aug 2012
School
University of Guelph
Department
Psychology
Course
PSYC 1000
Page:
of 3
Course: PSYC*1000 (DE)
Professor: Harvey Marmurek
Schedule: Summer, 2012
Textbook: Psychology – Tenth Edition in Modules authored by David G. Myers
Textbook ISBN: 9781464102615
Module 50: Schizophrenia
Nearly 1 in 100 people (about 60% of men) will develop schizophrenia, joining the estimated 24 million across the
world.
Symptoms of Schizophrenia
What patterns of thinking, perceiving, feeling, and behaving characterize schizophrenia?
Schizophrenia means split mind – not multiple-personality but rather split from reality that shows itself in
disorganized thinking, disturbed perceptions, and inappropriate emotions and actions. It is the chief example of a
psychosis, a disorder marked by irrationality and lost contact with reality.
Disorganized Thinking: Delusions – fragmented, bizarre, often distorted. Paranoid tendencies are prone to
delusions of persecution. Disorganized thoughts may result from a breakdown in selective attention. Irrelevant,
minute stimuli such as the grooves on a brick or the inflections of a oice may distract their attention from a bigger
event or a speaker’s meaning.
Disturbed Perceptions: hallucinations (sensory experiences without sensory stimulation). May see, feel,
taste, or smell things that are not there. Hallucinations are most often auditory – frequently voices making insulting
remarks or giving orders.
Inappropriate Emotions and Actions: Often utterly inappropriate, split off from reality – laughing at gramma’s
death, cring when others laugh, anger for no reason. Others with schizophrenia lapse into an emotionless state of
flat affect. Most also have difficulty perceiving facial emotions and reading others’ states of mind. Motor behaviour
may also be inappropriate. Some perform senseless, compulsive acts, such as continually rocking or rubbing an
arm. Others, who exhibit catatonia, may remain motionless for hours and then become agitated. During their most
severe periods, those with schizophrenia live in a private inner world, preoccupied with illogical ideas and unreal
images. Supportive environment and emdication – 40%+ will have periods of a year or more of normal life
experience.
Onset and Development of Schizophrenia
What are the schizophrenia subtypes? How do chronic and acute schizophrenia differ?
Strikes as young people are maturing into adulthood thin, young men, who were not breast-fed more vulnerable
(Swedish and Danish studies). Some – will appear suddenly and seem as a reaction to stress. For others it
develops gradually, emerging from a long history of social inadequacy and poor school performance. It is a cluster
of disorders. Positive symptoms may experience hallucinations, talk in disorganized and deluded ways, and exhibit
inappropriate emotions. Negative symptoms have toneless voices, expressionless faces, or mute and rigid bodies.
Thus, positive symptoms are the presence of inappropriate behaviours and negative symptoms are the absence of
appropriate behaviours. When schizophrenia is a slow-developing process (called chronic, or process
schizophrenia), recovery is doubtful. When previously well-adjusted people develop schizophrenia rapidly (called
acute or reactive schizophrenia) following particular life stresses, recovery is much more likely.
Understanding Schizophrenia
Schizophrenia is a disease of the brain manifest in symptoms of the mind
Brain Abnormalities
How do brain abnormalities and viral infections help explain schizophrenia?
Dopamine Overactivity: sixfold excess for the so-called D4 dopamine receptor. Such a hyper-responsive
dopamine system may intensify brain signals in schizophrenia, creating positive symptoms such as hallucinations
and paranoia. Drugs that block dopamine receptors often lessen these symptoms and drugs that increase
dopaimmine levels such as amphetamines and cocaine sometimes intensify them.
Abnormal Brain Activity and Anatomy: modern brain-scanning techniques reveal that many people with
chronic schizophrenia have abnormal activity in multiple brain areas. Some have abnormally low brain activity in the
frontal lobes, which are critical for reasoning, planning, and problem solving. Also display a noticeable decline in
brain waves that reflect synchronized neural firing in the frontal lobes. Out-of-sync neurons may disrupt the
integrated functioning of neural networks, possibly contributing o schizophrenia symptoms. PET scan while
hallucinating – brain became vigorously active in several core regions, including the thalamus, a structure deep in
the brain that filters incoming sensory signals and transmits them to the cortex. Another PET scan with paranoia
found increased activity in the amygdala, a fear processing centre. Found enlarged, fluid-filled areas and a
corresponding shrinkage and thinning of cerebral tissue in people with schiz. The greater the brain shrinkage, the
ore severe the thought disorder. One smaller-than-normal area is the cortex. Another is the corpus callosum
connection between the two hemispheres. Another is the thalamus, which may explain why people with schiz have
difficulty filtering sensory input and focusing attention. Schiz. Involves not one isolated brain abnormality but
problems with several brain regions and their interconnections. Caused by? Possibly prenatal development or
delivery – risks – low birth weight, maternal diabetes, paternal age, oxygen deprivation during delivery, wartime
famine.
Maternal Virus During Midpregnancy:
Are people at increased risk if, curing the middle of their fetal development, their country experienced a flu
epidemic – yes
Are people born in densely populated areas, where viral diseases spread more readily, at greater risk – yes
Are those born during winter and spring months – after the fall-winter flu season at increased risk – yes, but
small (5-8%)
In the southern hemisphere, where the seasons are the reverse of the northern hemispheres, are the
months of above-average schoz births similarily reversed – yes
Are mothers who report being sick with influenza during pregnancy more likely to bear children who develop
schiz – yes, during second trimester
Does blood drawn from pregnant women whose offspring develop schiz show higher-than-normal levels of
antibodies that suggest a vrgal infection – yes
Genetic Factors
Are there genetic influences on schizophrenia What factors may be early warning signs of schizophrenia in
children?
The nearly 1-in-100 odds of any person’s being diagnosed with schiz become about 1 in 10 among those whose
sibling or parent has the disorder, and close to 1 in 2 if the affected sibling is an identical twin. Some of these genes
influence the effets of dopamine and other neurotransmitters in the brain. Others affect the production of myelin, a
fatty substance that coats the axons of nerve cells and lets impulses travel at high speed through neural networks.
Genetic formula isn’t straightforward. Affected by many genes, each with very small effects. Genes not always
turned on.
Psychological Factors
Nicol and Gottesman noted 30 years ago that ‘no environmental causes have been disocered that will invariably or
even with moderate probability produe schiz in person who are not related to a person with schiz. High risk children
– those born to a parent with schiz or exposed to prenatal risks. Warning signs:
A mother whose schiz was severe and long-lasting
Birth complications, often involving oxygen deprivation and low birth weight
Separation from parents
Short attention span and poor muscle coordination
Disruptive or withdrawn behaviour
Emotional unpredictability
Poor peer relations and solo play
A person with schiz who has negative symptoms may have an expressionless face and toneless voice. These
symptoms are most common with chronic schiz and are not likely to respond to drug therapy. Those with positive
symptoms are likely to experience delusions and to be diagnosed with acute schiz which is much more likely to
respond to drug therapy.
What factors contribute to the onset and development of schizophrenia?
Biological factors include abnormalities in brain structure and function, prenatal exposure to a maternal virus, and
genetic factors. However, schiz is more likely to develop given a high-risk environment.
Schizophrenia: a group of severe disorders characterized by disorganized and delusional thinking, disturbed
perceptions, and inappropriate emotions and behaviours.
Psychosis: a psychological disorder in which a person loses contact with reality, experiencing irrational ideas and
distorted perceptions.
Delusions: false beliefs, often of persecution of grandeur, that may accompany psychotic disorders.
Mr. James believes that people are constantly laughing at him and that FBI agents are trying to steal his life
savings. Mr. James is most clearly suffering from delusions.
Which of the following best illustrates a negative symptom of schizophrenia? social withdrawal
Catatonia is characterized by periods of immobility or excessive, purposeless movement.
Therapeutic drugs that block dopamine receptors are most likely to reduce hallucinations.
The relationship between the season of the year in which people are born and their subsequent risk of
schizophrenia best highlights the role of ________ in this disorder. viral infections
Mrs. Higgins believes that aliens from another planet have removed her stomach and are watching her to see how
long it takes her to grow another one. Mrs. Higgins is most likely suffering from schizophrenia.
Michael complains that threatening voices are constantly telling him that he is so evil he should drown himself.
Michael is experiencing hallucinations.
The chances for recovery from schizophrenia are considered to be greatest when the disorder develops rapidly in
response to a stressful life situation.
A PET scan study of people with ________ found increased activity in the amygdala. paranoia
Oxygen deprivation at the time of birth is a known risk factor for schizophrenia.

Document Summary

Textbook: psychology tenth edition in modules authored by david g. myers. Nearly 1 in 100 people (about 60% of men) will develop schizophrenia, joining the estimated 24 million across the world. Schizophrenia means split mind not multiple-personality but rather split from reality that shows itself in disorganized thinking, disturbed perceptions, and inappropriate emotions and actions. It is the chief example of a psychosis, a disorder marked by irrationality and lost contact with reality. Disorganized thinking: delusions fragmented, bizarre, often distorted. Paranoid tendencies are prone to delusions of persecution. Disorganized thoughts may result from a breakdown in selective attention. Irrelevant, minute stimuli such as the grooves on a brick or the inflections of a oice may distract their attention from a bigger event or a speaker"s meaning. Disturbed perceptions: hallucinations (sensory experiences without sensory stimulation). May see, feel, taste, or smell things that are not there. Hallucinations are most often auditory frequently voices making insulting remarks or giving orders.