Clinical Characteristics and Explanations of Schizophrenia

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Clinical Characteristics of Schizophrenia

The symptoms of schizophrenia are typically divided into positive symptoms and negative symptoms.The DSM states that a diagnosis of schizophrenia requires a one month duration of 2+ positive symptoms.

Positive Symptoms

The patient's symptom is something that has been changed or gained and is an excess or distortion of their normal functioning.

  • Delusions - bizzare beliefs that seem real.
  • Experiences of control -belief they are being controlled by an alien force.
  • Hallucinations - unreal perceptions of environment.
  • Disordered thinking - thought have been inserted, broadcast or withdrawn from their mind.

Negative symptoms

The patient's symptom is a defficiency or dimunition of normal function; some function has been lost.

  • Emotional expression - significantly reduced.
  • Poverty of speech - lessening fluency/productivity.
  • Lack of goal-directed behaviour - e.g. not getting out of bed.
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Issues of Reliabillity


  • Refers to the consistency of a measuring instrument
  • Reliability can be measured in two ways; inter-rater reliability and test-retest reliability.

Inter-rater reliability

Assessing whether two assessors give similar results.

Carson in 1991 claimed that the DSM-III had inter-rater reliability.

Test-retest reliability

Assesses whether results are consistent over time

Takes a correlation over retests to measure reliability - RBANS (Repeatable Battery for the Assessment of Neuropsychological Status)  administered and correlation of +0.84 found.

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Evaluation of Reliability

  • Inter-rater reliability - little evidence DSM used with high reliability by health clinicians, correlations as low as +0.11
  • Test-retest reliability -measures of cognition vital in schizophrenic studies, Prescott analysed measures of cognition in 14 chronic schizophrenics - performance stable over 6 months.
  • Unreliable symptoms - for diagnosis, only one symptom required if delusions are bizzare. However how bizzare something is is subjective. 50 psychiatrists to differentiate between bizzare and non-bizzare delusions, correlations of only +0.40.
  • Comparing DSM and ICD - inter-rater reliability of the two >50% however schizophrenia more commonly diagnosed according to ICD-10.

Rosenhan's study

Sent normal people to psychiatric hospitals to pretend to be schizophrenia, saying they were having auditory hallucinations. They were all diagnosed with schizophrenia although none were, they weren't even recognised later on.

Follow up study, Rosenhan warned hospital's he'd be sending pseudopatients. This resulted in 21% detection rate although he sent none.

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Issues of Validity

Validity refers to the extent that a diagnosis represents something real and distinct from other disorders. Diagnoses cannot be valid without reliability.


The extent that two or more conditions co-occur - common among schizophrenics e,g, depression, substance abuse. More difficult to obtain validity when conditions co-occur.

Buckley et al. - co-morbidity affects 50% of patients, 47% lifetime diagnosis of co-morbid substance abuse.

Positive or negative symptoms

Positive symptoms are more useful for diagnosis.

Klosterkotter study of psychiatric admissions in Germany. Positive symptoms = valid diagnosis.


Little predictive validity regarding prognosis. Some improve, some don't and symptoms vary massively.

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Evaluation of Validity

  • Co-morbidity and medical complications- poor levels of functioning more to do with untreated co-morbid physical disorders not psychiatric disorder. Many patients diagnosed with hypothyroidism, asthma, diabetes, hypertension. Concluded that consequence of being schizophrenic is poor medical treatment which affects prognosis.Supports importance of co-morbidity and offers explanation for little predictive validity.
  • Co-morbidity and suicide risk - 40% for those with at least one co-morbid disorder compared to 1% for those without. Supports role of co-morbidity.
  • Ethnicity and misdiagnoses- rates of schizophrenia higher for African-Carribean's. Explained by poor housing, unemployment and social isolation (if disorder has psychological cause). May also be genetics/gene pool. May be misdiagnoses, cultural differences in mannerisms and language misunderstood by a white clinician - invalid diagnoses.
  • Issues with symptoms - symptoms overlap with other disorders. Dissociative Identity Disorder patients show more schizophrenic symptoms.
  • Cultural differences in diagnosis - Copeland gave US and UK psychiatrists description of patient, 69% US psychiatrists diagnosed with schizophrenia compared to 2% of UK. May be due to differences in education, classification system used -still highlights issue of validity and reliability.
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Biological Explanation of Schizophrenia

Genetic factors

  • Twin studies- Joseph found concordance rate for MZ twins 40% compared to 7.4% for DZ twins. Both MZ and DZ twins have same environments.
  • Adoption studies - Tienan 164 adopted children with schizophrenic mothers. 6.7% diagnosed with schizophrenia compared to 2% in control group (non-schizo mothers)
  • Family studies - biological relatives more affected that non-biological relatives? Closer degree of relation, greater the risk. Children with 2 schizophrenic parents concordance 46% those with one 13%.

The dopamine hypothesis

Excessive dopamine levels or oversensitivity of the brain to dopamine is cause of schizophrenia. Dopamine neurons play key role in guiding attention and perception.

Three main sources of evidence for hypothesis:

  • Amphetamines -dopamine agonist, large doses can cause symptoms
  • Anti-psychotics- dopamine antagonist, block dopamine, eliminates symptoms
  • Parkinson's disease - L-Dopa raises dopamine, schizphrenic side effects.
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Evaluation of Biological Explanation

  • Twin studies - MZ twins treated more similarly than DZ, environment reason for differences.
  • Adoption studies - adoptees selectively placed, history of child known,what type of person would adopt such a child?
  • Family studies - common rearing patterns e.g. negative emotional climate may be cause.
  • Post-mortem studies - drugs may causes sharp increase in dopamine as neurons compensate. Those who didn't have drugs before death had normal levels of dopamine.
  • Neuro-imaging research - PET scans more precise than studying metabolites and find no evidence of dopamine.
  • Evidence from treatment- anti-psychotics reduce symptoms. When compared with placebo, relapse rate 19% compared to 55%.
  • Methodological issues - when studying adoptees, definition of schizophrenia broadened to include spectrum disorders.No full schizophrenics found.
  • Evolutionary perspective - originated in ancestors to facilitate division in communities when resources were low, enhancing survival. Mood changes, delusions etc. would encourage discontented members to leave.
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Psychodynamic Explanation


  • Freud assumed that neuroses (e.g. depression and anxiety) occured as a result of severe conflicts and traumatic experiences stored in the unconcious mind.
  • He said schizophrenia was caused by regression (a defence mechanism) to the oral stage of psychosexual development.
  • Specifically, regression was to a state of primary narcissism (great self interest).
  • The loss of reality was because the ego was not working properly
  • Delusion of grandeur reflect idea of self importance.
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Evaluation of Psychodynamic Approach

  • Lack of evidence - little evidence to support theory. Very psuedoscientific.
  • Alternative explanations - psychoanalysts claim family patterns are cause, due to cold rejecting mothers. However this may be due to social learning or genetics.
  • Weakness- Schizophrenic behaviour not similar to infant behaviour. Weakens idea of regression to infant state.
  • Little predictive validity - many people have traumatic experiences in childhood but not all become schizophrenic.
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Cognitive Explanation

  • Approach focuses on cognition of schizophrenics i.e. perception, attention, language,memory and problem solving.
  • Almost certainly physiological abnormalities in schizophrenics which lead to cognitive deficits.
  • Cognitive deficits lead to reduced emotional expression, disorganised speech and delusions.
  • Vicious circle- cognitive deficits leave people vunerable, when they experience stressful events they cannot cope andso the resulting emotional pressure can lead to increased cognitive deficits.
  • Role of attention - cannot focus attention specifically so let in too much irrelevant information (interpret a very different world)
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Evaluation of Cognitive Approach

  • Doesn't explain cause of cognitive deficits; cognitive researchers turn to other approaches to find the cause i.e. physiological abnormalities are genetic.
  • Difficult to test cognition - based on tests, very little differences between those with schizophrenia and those with bipolar.
  • Evidence for physiological basis of cognitive deficits -Meyer-Lindenberg found a link between excess dopamine in prefrontal cortex and working memory
  • Suggested treatment  - Yellowlees used a machine that produces hallicinations to show patients hallucinations aren't real i.e. aim to change irrational thoughts. No evidence treatment is successful.
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Socio-Cultural Factors in Schizophrenia

Life events and schizophrenia.

Occurance of stressful life events associated with schizophrenia. Brown & Birley - prior to schizophrenic episode, patients who had previously experienced schizophrenia reported twice as many stressful life events. 50% of people experience stressful life event before an episode. Mechanism unknown, however high levels of physiological arousal associated with neurotransmitter changes.

Double-bind theory

Bateson et al- children who receive contradictory messages from parents more likely to experience schizophrenia - lead to self-doubt, confusion and withdrawal.

Expressed emotion

Negative emotional climate = high degree of EE. EE family communication style involving hostility, criticisms and emotional over-involvement. Influences relapse by 4 times. Stress beyond impaired coping mechanisms.

Labelling Theory

Social groups construct rules. Symptoms seen as deviant so label of schizophrenic applied. Then becomes self-fulfilling prophecy leading to further symptoms.

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Evaluation of Socio-Cultural Factors

Life events and schizophrenia
Van Os et al - reported no link. Those who experienced stressful event = lower relapse!
Correlation not cause. Beginnings of disorder may cause stressful events.

Importance of family relationships
Tienan's adoption study - adopted children with schizophrenic biological parents more likely to become ill. However difference only emerged where situations within adopted family were disturbed.

Double-bind theory
Berger-schizophrenics higher recall of double-bind situations. However recall may be affected by illness.
Liem - no differences in communication in schizophrenic families and normal families.

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Evaluation of Socio-Cultural Factors Continued

Expressed emotion
Is EE cause or effect?
Effective therapy developed to reduce EE, reduces relapse rates.
Kalafi & Torabi - high EE prevalent in Iran, main cause of relapse.

Labelling theory
Scheff evaluated 18 studies - 13 consistent with labelling theory and 5 inconsistent.
Rosenhan's study supports labelling theory.

Cultural differences
Findings on EE have been replicated cross-culturally. EE much less common in non-Western cultures as they're less individualistic so less likely to blame someone with schizophrenia.

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