Transcript teach-eng-mod2-10 - World Psychiatric Association

Some General Tests of
Cognition
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WAIS-R
Raven Progressive Matrices
Multilingual Aphasia Battery
Mini-mental Status Exam
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Some Tests of
Attention
• Continuous Performance
Task
• Trails A and B
• Stroop
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Some Tests of
Executive Function
• Wisconsin Card Sorting
Test
• Porteus Mazes
• Tower of London
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Wisconsin Card Sorting
Test
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Fluency
• Controlled Oral Word
Association
• Category Fluency
• Letter Fluency
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Verbal Memory
• Logical Memory (Wechsler
Memory Scale)
• Rey Auditory Verbal
Learning
• Paired Associated Learning
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Visual
Reconstructive
Memory
• Rey Osterreith Complex
Figure
• Benton Visual Retention
Test
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Neurophysiology
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Advantages of
Neurophysiological Techniques
• Noninvasive
• Acceptable to disturbed patients
• Require very little technical
equipment
• Inexpensive to use
• Good temporal resolution
• Can capture brain activity during
very brief periods
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Neurophysiological
Techniques
• Electroencephalography (EEG)
• Brain Electrical Activity Mapping
(BEAM)
• Event Related Potentials (ERPs)
• Smooth Pursuit Eye Movements
(SPEM)
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EEG and BEAM
• Neither currently has significant
research application in
schizophrenia
• No specific abnormalities found
with these tools
• EEG may be used clinically to
rule out a neurological or
medical condition
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Event Related Potentials
• Involve the study of brain
electrical activity in response to
some type of stimulus
• Can be used to study information
processing
• Have been useful in the search
for the mechanisms of
schizophrenia
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N100
• A negative wave occurring at 100
milliseconds after a stimulus
• Thought to be related to
selective attention
• Paradigms require that subjects
focus attention (e.g., dichotic
listening, or focussing attention
on the right or left ear while
hearing stimuli in both ears)
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P300
• A positive wave occurring at 300
milliseconds
• Increases in size when subjects are
given a new or unexpected type of
stimulus
• Decreased in schizophrenia, as
compared with normal controls
• Correlated with a decrease in temporal
lobe size
• Reflects an abnormality in attentional
resources or the ability to allocate them
• Improves with treatment
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P50
• Positive wave occurring at 50
milliseconds
• Used to study sensory gating
(the ability to filter stimuli, or to
inhibit irrelevant information)
• Abnormal in schizophrenic
patients and may also be
abnormal in first degree relatives
• A potential endophenotypic
“marker”
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Prepulse Inhibition
• The most widely used P50 paradigm
• Involves delivering a weak sensory
stimulus (the “inhibiting prepulse”)
prior to a very strong one that
would invoke a startle response
• P50 reduced in normals after
prepulse inhibition, but not in
patients with schizophrenia
• Implies a basic deficit in filtering or
gating information
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Smooth Pursuit Eye
Movements
• Evaluates the ability to smoothly
follow a visual target
• Abnormalities in schizophrenia
consistently replicated
• Abnormalities also observed in first
degree relatives
• Also a potential “endophenotypic
marker”
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Nongenetic
Factors
Birth Injuries
Viral Infections
Nutrition
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The Copenhagen High
Risk Study
• A prospective longitudinal study of
individuals at risk for schizophrenia
• 207 children of schizophrenic
mothers and 104 matched low risk
normal controls evaluated between
1962 and 1964
• Goal: to determine why some
individuals at risk become ill while
others do not
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Prenatal Injuries and
Obstetrical Complications
• Intrauterine bleeding
• Eclampsia or pre-eclamsia
• Forceps delivery, potentially
causing regional injury
• Prolonged labor, producing
hypoxia or tissue compression
• All carefully documented in the
Copenhagen High Risk Study
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Early Results
• Individuals who developed
schizophrenia had a higher rate of
obstetrical complications
• High risk individuals with schizotypal
disorder had a low rate of
complications
• Interpretation: schizophrenia is a
neurologically complicated form of
schizotypal disorder
• Schizotypal disorder might be a more
direct representation of the genetic
phenotype than schizophrenia itself
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Additional Information
Using CT Scanning
• Individuals who developed
schizophrenia had the largest
ventricles
• Individuals with schizotypal
disorder had the smallest
ventricles
• A modest correlation between
ventricular size and level of
perinatal complications
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Implications
• Pregnancy and birth complications may
be important contributing factors to the
development of schizophrenia
• Could be used for primary prevention in
high risk samples (e.g., close
monitoring, early medication use)
• However, such preventive strategies
also raise important ethical
considerations, such as creating
anxiety in the mother or self-fulfilling
prophecies in the child
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Viral Infections
• A frequently-replicated
relationship between season of
birth (winter birth) and increased
rates of schizophrenia
• Also a relationship between birth
in urban areas and increased
rates of schizophrenia
• Both these factors might
predispose to an increased rate
of viral infections, and in turn to
schizophrenia
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Direct Studies of
Influenza Epidemics
• First empirical report of an
increased rate of schizophrenia
after the 1957 influenza
pandemic in Finland published
by a Finnish group in 1988
• Subsequently, replications of the
findings have been reported from
Japan, England, Ireland,
Scotland, Wales, and Australia
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Implications
• The influenza virus could be a
contributing factor to the
development of schizophrenia
• Findings have epidemiological
significance, since influenza can
potentially be prevented through
vaccination
• No evidence for fetal risk in
connection with the vaccination
of pregnant women
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Nutritional Factors
• Studies of children born to pregnant
mothers who survived the “Dutch
Hunger Winter” of World War II
• Offspring have an increased risk for
schizophrenia
• Implicates nutrition as another
potential contributor to the
pathophysiology of schizophrenia
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Working Model
Etiology:
DNA Gene Expression Viruses Toxins Nutrition Birth Injury Psychological Experiences
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Pathophysiology:
Brain Development (e.g., neuron formation, migration, pruning, apoptosis)
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Neuronal Connectivity and Communication
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Impairment in a Fundamental Cognitive Process
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Impairment Second-Order Cognitive Processes
(e.g., attention, memory, language)
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Symptoms of Schizophrenia
(e.g., hallucinations, delusions, negative symptoms, disorganized speech)
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The Mechanisms and
Phenotype of Schizophrenia
• Multiple cumulative hits
• May affect brain development and connectivity at
multiple stages, with young adulthood being most
critical
• When sufficient hits accumulate, the phenotype
appears
• The phenotype is defined by a impairment in
some basic cognitive process (e.g., impaired
gating or filtering, cognitive dysmetria)
• Simple models of this type are heuristic and
facilitate the search for specific mechanisms or
preventive measures
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