Problem 4
Schizophrenia
Schizophrenia – disorder characterized by disordered thinking; faulty
perception and attention; lack of emotional expressiveness
o prevalence – around 1%
o gender – affects men slightly more often than women
o age of onset – usually in late adolescence or early adulthood; usually
somewhat earlier in men than in women
o high suicide rate
Positive Symptoms – for the most part, acute episodes of schizophrenia are
characterized by positive symptoms
Þ Delusions – beliefs contrary to reality and firmly held despite
disconfirming evidence
o delusions of control – believe an external force controls his/her
feelings, behaviours
• thought insertion – thoughts that are not his/her own have been
placed in his/her mind by an external source
• thought broadcasting – his/her thoughts are
transmitted/broadcasted, so that others know what he/she is thinking
• delusions of thought withdrawal– belief that one’s thoughts have been
removed by another source
o Delusions of persecution (paranoia) - belief that somebody wants to harm
them
o grandiose delusions – an exaggerated sense of his/her own importance,
power, knowledge, identity
o Delusions of reference– belief that specific gestures, comments, or even
larger environmental cues are directed directly to them
Þ Hallucinations – sensory experiences in the absence of any relevant stimulation
from the environment. more often auditory
o misattribute their own voice as being someone else’s
o neuroimaging studies found: strongest activation in Broca’s area (speech) +
speech processing and understanding in the temporal lobes (Wernicke’s area)
o somatic hallucinations – feel there is something wrong with their body
Negative Symptoms – consist of behavioural deficits in motivation, pleasure, social
closeness, emotion expression
Þ Avolition– refers to the lack of motivation and a seeming absence of interest in or
an inability to persist in what are usually routine activities (work, school, hobbies,
etc.)
motivation
Þ Asociality – severe impairments in social relationships or lack of interest in them
and pleasure – few friends, poor social skills
domain Þ Anhedonia – a loss of interest in or a reported lessening of the experience of
pleasure
o consummatory pleasure – the amount of pleasure experienced in the moment
or in the presence of something pleasurable
o anticipatory pleasure – the amount of expected pleasure from future
events/activities
o people with schizophrenia appear to have a deficit in anticipatory pleasure
but not consummatory pleasure
Þ Apathy – no motivation and interest in anything
,expression Þ Blunted affect – lack of outward expression of emotion
domain Þ Alogia – a significant reduction in the amount of speech – do not talk
Disorganised Symptoms
Þ Disorganised speech (formal thought disorder) – problems in organising ideas
and in speaking so that a listener can understand
o loose associations/derailment – the person may be more successful in
communicating with a listener but has difficulty sticking to one topic
o circumstantial thoughts/speech – the question is eventually answered (with a
lot of unnecessary details)
o tangential thoughts/speech – the patient never reaches the point they want to
make
o speech retardation – the individual may take a long time before answering a
question
Þ Disorganised Behaviour – seem to lose the ability to organise their behaviour and
make it conform to community standards
o have difficulty performing everyday tasks
o Catatonic behavior – the decreased or complete lack of reactivity to the
environment
o a range of catatonic behaviors:
• negativism - resistance to instruction
• mutism/stupor - complete lack of verbal and motor responses
• rigidity – maintaining a rigid or upright posture while resisting efforts
to be moved
• posturing - holding odd, awkward postures for long periods
• catatonic excitement – where the individual experiences hyperactivity
of motor behavior, in a seemingly excited or delirious way.
Types of symptoms: Not uncommon to have:
o prodromal symptoms – precede the active phase of the disorder
o residual symptoms – follow the active phase of the disorder
o These prodromal and residual symptoms are “subthreshold” forms of
psychotic symptoms that do not cause significant impairment in functioning,
with the exception of negative symptoms
Etiology
Genetic Factors
Þ Family Studies – relatives of people with schizophrenia are at increased risk, and
the risk increases as the genetic relationship with the person becomes closer
o negative symptoms may have stronger genetic component
Þ Twin Studies
o negative symptoms – stronger genetic component
o DZ twins – 12.08%; MZ – 44.30% -> still not a 100%
Þ Adoption Studies
o study those children who were reared apart from their schizophrenic
mothers, adopted by parents without schizophrenia
o study: 47 cases; 5 of them developed schizophrenia (10.6%)
Þ Familial High-Risk Studies – different type of family studies – begins with 1/2
biological parents with schizophrenia and follows their offspring longitudinally
o children with a parent with a schizophrenia spectrum disorder were 6 times
more likely to develop such disorder by age 40
Þ Molecular Genetics Research
o the predisposition for schizophrenia is not transmitted by a single gene
, o over 25 candidate genes have been identified
• DRD2 – dopamine receptor (D2)
• COMT – associated with cognitive control processes that rely on the
prefrontal cortex
- people with schizophrenia have deficits in cognitive control processes
(planning, working memory, problem solving)
Þ Clinical High-Risk Study – identify young people who are at risk of developing
schizophrenia
Role of Neurotransmitters
Þ Dopamine Theory – the theory that schizophrenia is related to excess activity of
the neurotransmitter dopamine
o based on the knowledge that medications reduce dopamine activity
o amphetamines, which increase dopamine activity, can produce a state that
closely resembles schizophrenia
o an excess of dopamine receptors appears to be related mainly to positive and
disorganization symptoms
o negative symptoms may be accounted for by other neurotransmitters (-)
o it is unlikely that a single neurotransmitter could account for everything (-)
Þ Other neurotransmitters
o serotonin – newer drugs also block serotonin receptors
o GABA – disrupted in the PFC; dopamine neurons generally modulate the
activity of other neural systems
o glutamate – low levels of glutamate have been found in the cerebrospinal fluid
of people with schizophrenia
o NMDA – receptors part of the glutamate system - drugs which interfere with
these receptors can induce positive + negative symptoms. NMDA deficits
account for cognitive deficits and disorganization
Brain Structure and Function
Þ Enlarged ventricles – spaces in the brain filled with cerebrospinal fluid
o having larger fluid-filled spaces implies a loss of brain cells
o correlated with impaired performance on neuropsychological tests
o modest enlargement
Þ Factors Involving the Prefrontal Cortex
o PFC known to play a role in behaviours such as speech, decision making,
emotion, etc.
o reductions in grey matter and overall volume size in the PFC
o despite the reduced grey matter in the PFC, the number of neurons does not
appear to be reduced
• what is lost may be dendric spines
o less activation in PFC = more severe negative symptoms
Þ Problems in Temporal Cortex & Surrounding Regions
o structural and functional abnormalities in the temporal cortex (incl. temporal
gyrus, hippocampus, amygdala, etc.)
o reduction in cortical grey matter in temporal as well as frontal brain regions
o reduced volume in basal ganglia, hippocampus, limbic structures
o HPA axis – closely connected
• people with schizophrenia – more reactive to stress
• stress reactivity and a disrupted HPA axis –> reductions in
hippocampus volume
