Download Schizophrenia Circuit 14

Causes of Schizophrenia: Genetics and Environment
Numerous studies indicate that schizophrenia has a strong genetic component. Irving
Gottesman (1991) compiled data showing that the risk of developing schizophrenia
increases with the degree of biological closeness to someone suffering from the disorder.
While the general population has a 1 percent risk of developing schizophrenia, the chance
of being diagnosed with the disorder increases to 9 percent if a sibling is afflicted. If an
identical twin is diagnosed with schizophrenia, the likelihood of the other twin developing
the disorder jumps to 50 percent.
The fact that dizygotic (fraternal) twins show a higher rate of concordance than non-twin
siblings (17 percent compared to 9 percent) indicates that the prenatal environment may
playa role in developing schizophrenia. Mothers who contract rubella or influenza during
the second trimester of pregnancy aretwice as likely to give birth to children who develop
the disorder (Brown et al., 2000). However, whether this risk factor is due to the virus
itself, the mother's immune response, medications taken to combat the virus, or another,
unknown factor, is still unclear.
If schizophrenia were entirely controlled by genes, the risk of twoidentical twins both
developing the disorder should be close to 100 percent. That the concordance rate ishalf
this suggests that both genetics and environment play significant roles in the
development of schizophrenia. Some psychologists propose the diathesis-stress
hypothesis, which suggests that people are genetically predisposed to a particular mental
disorder but will develop the disorder only if they are exposed to environmental or
emotional stress during critical developmental periods.
Schizophrenia: What is It?
Literally meaning "split mind," schizophrenia is often mistaken for dissociative identity
disorder, a controversial condition in which people claim to have multiple personalities.
However, schizophrenia actually refers to a person's split from reality, characterized
by distorted perceptions, inappropriate emotions or reactions, and confusion.
Schizophrenia is classified as a psychotic disorder or a psychosis, which is a
psychological disorder in which a person loses contact with reality and expresses irrational
ideas and distorted perceptions.
To be diagnosed with schizophrenia, a person must display two or more symptoms for at
least a month. People with schizophrenia often think or speak in ways that are
disorganized, illogical, or incoherent. Schizophrenics may also suffer from delusions,
which are persistent, false beliefs. For example, patients may believe that they are being
spied on, that someone is controlling their thoughts and actions, or that people are being
unfaithful to them. These delusions may be supported by illogical thinking: Psychiatrist
SilvanaArieti (1955) noted the huge gap in one patient's reasoning when she asserted "The
Virgin Mary was a virgin. I am a virgin; therefore I am the Virgin Mary,"
A third symptom of schizophrenia is the existence of hallucinations: false sensory
perceptions that a person believes to be real. Hearing voices is the most common type of
hallucination; many schizophrenics report that they hear insulting comments or receive
orders from voices inside their heads. Research using fMRI scans shows that verbal
hallucinations in schizophrenics are accompanied by activity in the brain regions normally
associated with thought processing (Shergill et al., 2000). While auditory hallucinations
are most common, people may also see, feel, smell, or taste things that aren't really there.
Schizophrenics often have difficulty acting appropriately in social situations. They may
become catatonic and remain motionless for several hours, or they may become wildly
agitated and talk or shout constantly.
Clusters of symptoms can help to categorize schizophrenia. People who show positive
symptoms reflect an excess or distortion of normal functions, such as delusions and
hallucinations. These symptoms tend to appear and disappear as the disorder recurs and
goes into remission. Disorganized symptoms, such as confused speech and flat emotion,
follow the same pattern. However, schizophrenics who display negative symptoms,or
decreases in normal functions such as attention or emotion, tend to exhibit more constant
symptoms that are less responsive to antipsychotic medications.
EXPLAINING SCHIZOPHRENIA: Cognitive and Neural Abnormalities
Cognitive deficits are a core feature of schizophrenia. People with schizophrenia tend to
perform poorly on many information processing tasks, particularly activities that require
sustained attention. Working memory is permanently and consistently impaired, while
long-term memory involving the acquisition and recall of new information may be
severely impaired (Saykin et al., 1991). Since it is difficult for people with schizophrenia to
remember the source of a piece of information, it is likely that they will be unable to
distinguish between factual information and fiction or imagination, resulting in the
delusions characteristic of the disorder.
Do chemical imbalances in the brain explain schizophrenia? When researchers
examined the brains of schizophrenic patients after death, they discovered up to six times
the normal number of dopamine receptors (Seeman et al., 1993) The researchers believe that
this elevated level of dopamine may intensify brain signals in schizophrenic patients,
causing positive symptoms such as hallucinations and paranoia. Drugs that block
dopamine transmission have proved effective at reducing many of the symptoms of
schizophrenia, whereas drugs that increase dopamine action, such as cocaine or
amphetamines, can exacerbate symptoms (Swerdlow&Koob, 1987).
Recent research suggests that defects in the major receptor molecules for glutamate,
another neurotransmitter, may cause symptoms of schizophrenia. A glutamate deficiency
is linked to the negative symptoms associated with catatonic schizophrenia. This would
account for general cognitive defects, as well as explaining the effects of street drugs such
as PCP (commonly known as "angel dust"), which interfere with glutamate transmission
and temporarily induce schizophrenia-like symptoms in otherwise normal people.
Brain scans reveal that people with schizophrenia tend to have abnormal brain
structures. Many studies have found enlarged, fluid-filled areas and a corresponding
shrinkage of cerebral tissue in people with schizophrenia (Wright et al., 2000). Some studies
have even found such abnormalities in the brains of people who would later develop this
disorder, and in their close relatives. (Boos et al., 2007; Job et al., 2006).There is also evidence
of abnormally low activity in the frontal lobes (Pettegrew et al., 1993).
What causes these abnormal brain structures to form? Well, during adolescence the brain
selectively prunes unused neurons and connections. Some neuroscientists believe that
abnormal pruning may lead to the loss of too many cell bodies, potentially causing
symptoms of schizophrenia. Australian researcher Chris Pantelis and his colleagues took
MRI scans of three groups of young peopleone group of people who had recently been
admitted to hospital with schizophrenia, one group of people without schizophrenia, and
one group of people who had suffered from the disorder for around ten years. Pantelis
discovered that the brains of the first group were shrinking at twice the rate of those
without schizophrenia, suggesting that the normal developmental pruning process is
accelerated in the brains of people with schizophrenia (Salleh, 2003).
Treating Schizophrenia
Antipsychotic drugs are a class of psychoactive medications used to treat disorders in
which psychotic symptoms, such as hallucinations, paranoia, and delusions, predominate.
There are two types: typical and atypical.
Although many typical antipsychotics have been around since the 1950s, they continue to
be as effective as newer medications at treating psychotic illnesses such as schizophrenia.
These drugs effectively reduce or eliminate the positive symptoms of schizophrenia, such
as hallucinations and delusions, by decreasing dopamine activity at certain synapses in the
brain (Lehman et al., 1998; Lenzenweger et al., 1989). The relative effectiveness of these
drugs indicates that too much dopamine is at least partially responsible for schizophrenia
(Pickar et al., 1984; Taubes et al., 1994). A notable limitation of typical antipsychotics,
however, is that they do not treat negative symptoms. In addition, side effects of typical
antipsychotics can include sluggishness, tremors, and even tardive dyskinesia, a serious
and often irreversible motor disturbance in which the tongue, face and other muscles
involuntarily jerk or contract (Kaplan &Saddock, 1989). As a result of these potentially
severe side effects, people with psychotic illnesses often find it difficult to continue taking
antipsychotic medications for extended periods of time.
For those afflicted with negative symptoms of schizophrenia, such as apathy or prolonged
lack of movement, atypical antipsychotics can provide relief. These newer medications
can alleviate negative symptoms by altering the activity of other neurotransmitters, such as
serotonin, in addition to dopamine. They are also less likely to produce the major side
effects caused by typical antipsychotics because they target specific dopamine receptors in
the brain. Examples of atypical antipsychotics include Clozapine, Risperidone, and
Olanzapine. Although atypical antipsychotics generally produce fewer side effects than do
typical antipsychotics, both types of drugs can cause symptoms such as dizziness, weight
gain, and nausea.
AP Psychology
Schizophrenia Circuit
Name ___________________________
Please respond to the following questions based on each of the following sources.
Schizophrenia: What is It?
1. Why is schizophrenia considered to be a psychotic disorder?
2. What is the difference between a delusion and a hallucination?
3. Name and describe the three main categories of symptoms of schizophrenia.
1.
2.
3.
Causes of Schizophrenia: Genetics and Environment
1. What evidence exists to support the idea that schizophrenia has genetic causes?
2. What types of environmental factors contribute to the onset of schizophrenia?
3. Explain the diathesis-stress hypothesis.
Subtypes of Schizophrenia
Match each case study with the appropriate subtype of schizophrenia it best reflects.
Paranoid
Catatonic
Disorganized
Delusions of grandeur and Non-reaction to the
Disorganized speech,
persecution, often
environment, extreme
flattened or inappropriate
accompanied by
negativism, or wild
emotion
hallucinations
agitation
Case Study:
Case Study:
Case Study:
Undifferentiated
Varied symptoms
Explaining Schizophrenia: Cognitive and Neural Abnormalities
1. Identify two specific cognitive deficits associated with schizophrenia.
2. What role does dopamine play in causing schizophrenia?
3. A deficiency in glutamate is associated with which type of symptoms of schizophrenia?
4. Describe the abnormal brain structures associated with schizophrenia.
Treating Schizophrenia
1. How do typical antipsychotics eliminate the positive symptoms of schizophrenia?
2. What is tardive dyskinesia and why might it cause someone to stop taking typical antipsychotic
medication?
3. How do atypical antipsychotics help schizophrenics and what advantage do they have over typical
antipsychotics?
Anderson Cooper: Schizophrenia Simulator
1. What cognitive difficulties does Cooper exhibit during his schizophrenia simulation?
2. How does Cooper describe his experience? What caused him to feel empathy for people with
schizophrenia?
AP Psychology
Schizophrenia
Name ____________________________
Due TOMORROW!
Assignment: Respond to the following free-response question. You do not need to include an
introduction or conclusion. Respond to each bullet point in a separate paragraph. Be sure to write in
complete sentences. You will earn credit for completing this assignment -- it’s worth 10 points for Q1!