Chapter 94. Explaining Schizophrenia

Learning Objectives

cortex
outermost layers on the surface of the brain, where most cognitive processing occurs
dopamine
neurotransmitter involved in movement and motivation; excessively high levels may produce distortions in perception or thinking
frontal lobe
front portion of each hemisphere; initiates speech and muscle movements; involved in planning and decision-making
glutamate
most common excitatory neurotransmitter in the brain; typically increases brain activity and behavior
neurotransmitters
chemical messengers released by the axon terminal into the synaptic gap between neurons
interaction
the combined result of influences from two or more factors; typically, the presence of one factor changes the impact of the other factor
prenatal
referring to the period of development between conception and birth
psychological disorder
a disturbance in a person’s thinking, behavior, or emotions serious enough to cause distress
receptor
special area on a neuron's membrane that can bind with neurotransmitters
schizophrenia
a psychological disorder characterized by disturbed, irrational thinking and inappropriate emotional behavior
stress
the body’s response to a threat or challenge
Explaining Schizophrenia
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Learning Objectives:

Describe some of the biological influences that increase the risk of schizophrenia.

Describe some of the environmental influences that increase the risk of schizophrenia.

Review

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1. Schizophrenia is a complex psychological disorder that usually develops as biological predispositions interact with environmental events that trigger the disorder.

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2. The biological influences on schizophrenia include genetic factors that may shape the structure or function of key areas in the frontal lobes of the brain’s cortex—areas that are related to rational thinking and goal-oriented behavior.

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3. Genetic factors also influence the levels of dopamine and glutamate, two types of neurotransmitters linked to schizophrenia. Having an excess number of synaptic receptors for dopamine may predispose a person to develop schizophrenia.

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4. The most important environmental influences are prenatal events that interfere with normal development. Mothers who have influenza or other viral infections during pregnancy, or who suffer a nutritional deficiency, may give birth to babies with higher risk of developing schizophrenia.

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5. In addition, complications during the birth process may deprive the brain of oxygen, perhaps damaging sensitive brain areas in a way that could lead to a person developing schizophrenia in adulthood.

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6. These genetic influences and early environmental influences may increase the likelihood of schizophrenia. However, in a vulnerable individual, the actual disorder is probably triggered by severe stress experienced during adolescence or early adulthood.

Practice 1: Biological Influences

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Practice 1: Biological Influences

Roll over each influence to view an explanation of its role in schizophrenia.

Brain structure

Genetic influences

Brain chemistry

Causes of schizophrenia:

Individuals who suffer from schizophrenia often have abnormalities in the structure or activity levels of several brain areas, including the frontal lobe of the cortex.
Many people with schizophrenia show brain shrinkage, with fluid replacing the lost brain tissue.

Schizophrenia tends to run in families.
Inherited genes predispose some people to schizophrenia, and the closer the genetic relationship to someone suffering from schizophrenia, the higher the risk.
Adopted children who grow up with a parent who suffers from schizophrenia have a much lower risk than biological children of that same parent.

Individuals who suffer from schizophrenia have a higher-than-normal number of receptors for the neurotransmitter dopamine.
In contrast, activity of the neurotransmitter glutamate is low in some people with schizophrenia.

Practice 2: Environmental Influences

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Practice 2: Environmental Influences

Roll over each factor to view an explanation of its role in schizophrenia.

Prenatal virus

Nutritional deficiency

Birth complications

Causes of schizophrenia:

The risk of developing schizophrenia rises if the person's mother had influenza or other viral illnesses during pregnancy.
Researchers believe that the viral infection—or the mother's immune response to the infection—may impair fetal brain development, leading to greater risk of developing schizophrenia in adulthood.

The risk of developing schizophrenia rises if the person's mother lived in an area of famine or high poverty during pregnancy.
Brain development requires a large and steady intake of protein, so babies born to malnourished mothers may have brain abnormalities that make them vulnerable to developing schizophrenia.

During difficult births, the baby's brain may suffer oxygen deprivation. Severe oxygen deprivation produces cerebral palsy, but more minor deprivation may still damage the brain enough to raise the risk of later developing schizophrenia.

Quiz 1

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Quiz 1

Drag each of the factors for schizophrenia to one of the gray areas in the appropriate category. When all the factors have been placed, select the CHECK ANSWER button.

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Perhaps you should go back to review biological and environmental influences on schizophrenia.
Biological Influences
Environmental Influences
Brain shrinkage
Birth complications
Genetic predisposition
Prenatal virus
Oxygen deprivation
Nutritional deprivation
Low glutamate activity
Excess dopamine receptors

Quiz 2

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Quiz 2

Read the scenario, and then drag three of the six factors to the appropriate locations to complete the sentences. When all the sentences have been completed, select the CHECK ANSWER button.

Select the NEXT button and move to the Conclusion.
Perhaps you should go back to review the principles of concept formation.
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Jeremy is in his late teens, and he's beginning to exhibit some of the symptoms of schizophrenia. Based on current research on the causes of schizophrenia, we can make some suggestions for Jeremy's psychiatrist to explore.

occipital
frontal
protein surplus
viral infection
glutamate
dopamine

Jeremy’s brain development may have been impaired by a
during the prenatal period.

Jeremy may have an excessively high number of receptors for the
neurotransmitter.

Jeremy may have abnormalities in the structure or function of the
lobes of the brain’s cortex.

Conclusion

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