Transcript Schizophrenia - UCSD Cognitive Science

COGNITIVE
SCIENCE
17
The Brain
Gone Bad
Part 1
Jaime A. Pineda, Ph.D.
Meshberger, JAMA 264:1837-1841
Schizophrenia is a PSYCHOTIC
DISORDER
A severe mental disorder in which
thinking and emotion are so impaired that
the individual is seriously out of contact
with reality.
Progression of Schizophrenia
Louis Wain
Early onset schizophrenia: Wave of gray matter loss begins in parietal cortex and spreads forward
Schizophrenia
Refers to a group of disorders
There is not one essential symptom that must be
present for a diagnosis.
Instead, patients experience different
combinations of the main symptoms of
schizophrenia.
It is NOT split or multiple personality disorder.
Two Categories of Symptoms in
Schizophrenia
• Positive symptoms
• Negative symptoms
Positive Symptoms
• Distortions or excesses of normal functioning
–
–
–
–
–
delusions,
hallucinations,
disorganized speech,
thought disturbances,
motor disturbances
• Positive symptoms are generally more
responsive to treatment than negative symptoms
Delusions
• False beliefs that are firmly and
consistently held despite disconfirming
evidence or logic
• Individuals with mania or delusional
depression may also experience
delusions.
• However, the delusions of patients with
schizophrenia are often more bizarre
(highly implausible).
Types of Delusions
• Delusions of Grandeur
– Belief that one is a famous or powerful
person from the past or present
• Delusions of Control
– Belief that some external force is trying to
take control of one’s thoughts (thought
insertion), body, or behavior
Examples of Delusions of Control
Believing that thoughts that are not your own
have been placed in your mind by an external
source
A 29-year-old housewife said, “I look out of the
window and I think the garden looks nice and
the grass looks cool, but the thoughts of
Eamonn Andrews come into my mind. There
are no other thoughts there, only his… He
treats my mind like a screen and flashes his
thoughts on it like you flash a picture.”
Examples of Delusions of Control
Believing that your behavior is controlled by an
external force
A 29-year-old shorthand typist described her
(simplest) actions as follows: “When I reach my
hand for the comb it is my hand and arm which
move, and my fingers pick up the pen, but I
don’t control them… I sit there watching them
move, and they are quite independent, what
they do is nothing to do with me… I am just a
puppet who is manipulated by cosmic strings.
When the strings are pulled my body moves
and I cannot prevent it.”
Types of Delusions
• Thought Broadcasting
– Belief that one’s thoughts are being broadcast
or transmitted to others
• Thought Withdrawal
– Belief that one’s thoughts are being removed
from one’s mind
Types of Delusions
• Delusions of Reference
– Belief that all happenings revolve around
oneself, and/or one is always the center of
attention
• Delusions of Persecution
– Belief that one is the target of others’
mistreatment, evil plots, and/or murderous
intent
Hallucinations
• Sensory experiences in
the absence of any
stimulation from the
environment
• Any sensory modality
may be involved
–
–
–
–
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auditory (hearing);
visual (seeing);
olfactory (smelling);
tactile (feeling);
gustatory (tasting)
• Auditory hallucinations
are most common
Common Auditory Hallucinations in
Schizophrenia
• Hearing own thoughts spoken by another
voice
• Hearing voices that are arguing
• Hearing voices commenting on one’s own
behavior
Disorganized Speech /
Thought Disturbances
• Problems in organizing ideas and
speaking so that a listener can understand
• Loose Associations (cognitive slippage)
– continual shifting from topic to topic without
any apparent or logical connection between
thoughts
• Neologisms
– new, seemingly meaningless words that are
formed by combining words
Disorganized Motor Disturbances
• Extreme activity levels (unusually high or
low), peculiar body movements or
postures (e.g., catatonic schizophrenia),
strange gestures and grimaces
Negative Symptoms
• Behavioral deficits that endure beyond an
acute episode of schizophrenia
• More negative symptoms are associated
with a poorer prognosis
• Some negative symptoms might be
secondary to medications and/or
institutionalization
Types of Negative Symptoms
• Anhedonia
– inability to feel pleasure; lack of interest or
enjoyment in activities or relationships
• Avolition
– inability or lack of energy to engage in routine
(e.g., personal hygiene) and/or goal-directed
(e.g., work, school) activities
Types of Negative Symptoms
• Alogia
– lack of meaningful speech, which may take
several forms, including poverty of speech
(reduced amount of speech) or poverty of
content of speech (little information is
conveyed; vague, repetitive)
• Asociality
– impairments in social relationships; few
friends, poor social skills, little interest in
being with other people
Types of Negative Symptoms
• Flat Affect
– No stimulus can elicit an emotional response
– Patient may stare vacantly, with lifeless eyes
and expressionless face.
– Voice may be toneless.
– Flat affect refers only to outward expression,
not necessarily internal experience.
Genetic Studies
•
•
•
•
Twin
Blood relatives
Adoption
High-risk populations
(e.g., children of
schizophrenic
parents)
– Calcineurin and shortterm memory
(Tonegawa, 2003)
09_05
KH2F0905
60
First-Degree Relative
50
46%
Second-Degree Relative
48%
Third-Degree Relative
40
Percentage
30
of Risk
Unrelated Person
20
17%
13%
9%
10
1%
2%
2%
2%
5%
4%
6%
6%
0
Spouse
First
Cousin
General
Population
Grandchild Half
Sibling
Uncle
or Aunt
Nephew
or Niece
Parent
Offspring of Offspring of
One
Two
Schizophre- Schizophrenic Parent
nic Parents
Sibling
Relationship to Schizophrenic Person
Fraternal Twin
Identical
Twin
Biological Finding
• The Dopamine Hypothesis
– Disturbed functioning in dopamine system
(i.e., excess dopamine activity at certain
synaptic sites)
• Supportive evidence:
– Phenothiazines reduce dopamine activity and
psychotic symptoms are reduced;
– L-Dopa and amphetamines increase
dopamine activity and can produce psychotic
symptoms
Problems
• A large minority of people with schizophrenia
are not responsive to antipsychotic medications
affecting dopamine.
• Other effective medications (Clozapine) work
primarily on serotonin, rather than dopamine,
system.
• Antipsychotic drugs block dopamine receptors
quickly, but relief from symptoms is not seen for
weeks.
Biological Finding
• Enlarged ventricles (i.e.,
spaces) in the brain
and/or decreased volume
in frontal & temporal
lobes
• Indicates deterioration or
atrophy of brain tissue
• Supportive evidence: CT
scan & MRI studies
Problems
• Differences are relatively small
compared with control groups, and
many schizophrenic patients fall within
normal range.
• Reported in only 6 to 40 percent of
schizophrenic patients in a variety of
studies.
• Also reported in some patients with
mood disorders.
Biological Finding
• Low relative glucose
metabolism in frontal
areas
Problems
• Participants are generally chronic patients
on heavy neuroleptic medications.
• Some evidence indicates that
antipsychotic medications influence
cerebral blood flow even in patients who
are currently medication free.
Biological Finding
• Cognitive
dysfunctions
(visual
processing,
attention
problems, recall
memory
problems)
Problems
• Some members of control groups also
have such dysfunctions.
• May be a result of medication,
hospitalization, or other such variables.
• Validity of measures is questionable.
Environmental Factors
• Family
Characteristics
• Social Class
Social Class and Schizophrenia
• Schizophrenia is most common at lower
socioeconomic status (SES) levels
• Breeder Hypothesis
– stressors associated with low SES
increase the likelihood that schizophrenia
will develop
• Downward Drift Theory
– individuals with schizophrenia drift into low
SES areas because they cannot function in
other environments