Schizophrenia

Two diagnostic materials used for schizophrenia

DSM

ICD-10

Positive symptoms of schizophrenia

Excess of normal functions → pathological excess or distortion = add to person’s personality

• Delusions

• Hallucinations

Positive symptoms of schizophrenia: delusions

Irrational false beliefs

Remain unchanged even when individual is presented with conflicting evidence

Completely disconnected from reality → often appears bizarre to others

Positive symptoms of schizophrenia: hallucinations

Sensory perceptions → occur in absence of external stimulus

Vivid + involuntary + perceived as being located in external space (rather than in individual’s imagination)

Can happen in any of the senses = any modality

Negative symptoms of schizophrenia

Loss of normal functions → often persist more + more resistant to traditional antipsychotic treatments

• Avolition

• Speech poverty

Negative symptoms of schizophrenia: avolition

Total lack of motivation to initiate + persist in self-directed + purposeful activities = apathy

Signs of avolition = Andreasen identified clear indicators ~ failure to maintain personal hygiene, lack of persistence in work or school

Negative symptoms of schizophrenia: speech poverty

Alogia

Significant reduction in amount or fluency of speech

Reflects disruption in thought process rather than physical inability to speak

Comorbidity

Occurrence of two or more distinct clinical conditions in single patient

Schizophrenia rarely exists in isolation = complicates “descriptive validity” of disorder

Schizophrenia comorbidity: Buckley et al

A → quantify prevalence of comorbid psychiatric conditions in schizophrenic patients

P → review clinical data from patients diagnosed with schizophrenia

F → 50% = comorbid depression, 47% = substance abuse, 29% = PTSD, 23% = OCD

C → high comorbidity = suggests scz may not be distinct category → may lead to inconsistent diagnosis + inefficient treatment

Schizophrenia comorbidity: AO3

Reduces validity in diagnosing + treating schizophrenia → due to overlapping symptoms

Bias in scz diagnosis: gender bias

Men : women scz diagnosis = 4:1

Diagnostic criteria = applied inconsistently between men vs women → often leads to under-diagnosis in females

Suggests validity of diagnosis of scz = poor

Gender bias in diagnosis: Loring and Powell

A → test if patient’s gender influences psychiatrist’s diagnosis

P → 290 psychiatrists evaluated identical case studies → only gender was changed

F → patient labelled male = 56% diagnosed scz vs patient labelled female = 20% diagnosed scz

C → women = under-diagnosed → often maintain higher interpersonal functioning = masks severity of symptoms to clinicians

Bias in scz diagnosis: culture bias

Misinterpretation of cultural norms as scz symptoms

Assuming British cultural standards are ‘correct’

• Afro-Caribbean descent = 7 times more likely to be diagnosed vs white citizens ~ Cochrane (in Britain)

• Western clinicians → label “hearing voices” = hallucination

  • Spiritual norm in some African cultures

• Leads to unfair institutionalisation of minority groups

Symptom overlap

Different disorders share identical clinical features.

Patients could be diagnosed with multiple conditions simultaneously → depends on which symptoms clinician prioritises

Ambiguity = results in misdiagnosis + delays in appropriate pharmacological intervention

Symptom overlap: Cheniaux et al

A → investigate reliability + validity of scz diagnosis

P → two psychiatrists independently assessed 100 patients → using DSM + ICD-10

F → diagnosed 26 with scz using DSM + 44 using ICD vs diagnosed 13 with DSM + 24 with ICD

C → lower inter-rater reliability is low

Biological approach to schizophrenia

Asserts scz = physical illness

Focuses on:

• Genes

• Dopamine

• Brain structure

Biological approach to schizophrenia: genetic correlates

Polygenic = many genes contribute → no single gene responsible

• Large number of genes = ones that affect dopamine neurotransmitter production

Aetiologically heterogeneous = different genetic combinations can produce same symptoms

Ripke → found 108 separate genetic variations associated with scz

Biological approach to schizophrenia: genetic explanations → twin studies

Gottesman → mz twins = 48% concordance rate vs dz twins = 17% concordance rate

• Indicates genetic factor involved → not purely biological

• MZ twins = 100% same genetic data + similar environment

• DZ twins = ~50% same genetic data + similar environment

• Difference between concordance rate should be entirely due to genetic factors → not demonstrated in this study

Biological approach to schizophrenia: genetic explanations → adoption study

Tienari → Finnish adoption study = longitudinal study with 19000 ppts

• Two groups of adopted children → schizophrenic bio mother vs non scz bio mother

• Studied whether genetics or environment influence scz

• Scz bio mother = 7% developed scz

• Non scz bio mother = 1.5% developed scz

• Supports genetic influence → but evident other factors are involved

• Supports stress-diathesis model

Biological approach to schizophrenia: dopamine hypothesis

Imbalance of neurotransmitter of dopamine → drives symptoms of scz

Hyperdopaminergia (excess) → especially in subcortex + Broca’s area

• Linked to positive symptoms ~ auditory hallucinations → over-active neurons

Hypodopaminergia (deficit) → especially in prefrontal cortex

• Linked to negative symptoms ~ avolition

Biological approach to schizophrenia: dopamine hypothesis → empirical validation

Curran et al

A → observe effects of dopamine agonists on scz symptoms

P → amphetamines (inc dopamine levels) administered to scz + control group

F → induced psychotic symptoms in healthy controls + significantly increased existing symptoms in scz patients

C → indicate elevated dopamine levels = physiological trigger for scz

Biological approach to schizophrenia: neural correlates

• Patterns of structures + activity in brain associated with scz experience

Ventricle enlargement

• Ventricles = fluid-filled cavities in brain

• Research has consistently shown → scz patients often have significantly larger ventricles vs healthy controls

• Suggests that the surrounding brain tissue has shrunk or failed to develop, particularly in the pre-frontal cortex.

Regional activation + symptoms

• Ventral striatum = one of main reward centres → anticipation of reward

  • Juckel measured activity levels here → lower levels of activity in scz

  • Avolition

• Auditory hallucinations → Allen et al found lower activation levels in superior temporal gyrus during hallucinatory episodes.

• Speech poverty → reduced activity in Wernicke’s area (speech comprehension) is negatively correlated with the severity of thought disorders

Biological approach to schizophrenia: AO3

+ Scientific credibility → empirical + reliable + replicable methods
- Issue of causation ~ brain scans show enlarged ventricles → causing scz or caused by scz?

- Environmental influence → mz twins only have a 48% concordance rate = scz is not solely biological ~ environmental factors interact + trigger the vulnerability to scz

- Reductionist → ignores cognitive factors in the explanation of scz

Biological treatments: drug therapy

Antipsychotics = drugs that reduce psychotic symptoms ~ hallucinations

Biological treatments: drug therapy → typical psychotics

• Primary treatment for scz → introduced 1950s

• Chlorpromazine

• Dopamine antagonists → block dopamine receptors in brain

  • Targets D2 receptors in mesolimbic pathway (reward + sensory)

• Drastically reduces psychotic symptoms ~ hallucinations

• Influence histamine receptors → secondary interaction = used to calm highly anxious + aggressive patients

• Side effects:

  • Increased heart rate

  • Tardive dyskinesia = involuntary facial movements

Biological treatments: drug therapy → atypical psychotics

• Secondary/modern → introduced 70s then 90s

• Clozapine + risperidone

  • Clozapine = comorbid depression → reduces suicidal tendencies up to 80% (30-50% scz attempt suicide)

  • Risperidone = higher affinity → as useful in lower doses

• Bind to dopamine receptors + modulate serotonin

  • Block dopamine + increase serotonin

• Clozapine = glutamate agonist → increases

  • Glutamate = brain’s primary excitatory neurotransmitter → responsible for 90%+ of excitatory signalling + essential for learning + memory + normal neural communication

• Side effects

  • Weight gain

  • Clozapine → agranulocytosis = autoimmune condition affecting WBC → fatal seizure risk

Biological treatments: drug therapy → Bagnall study

A → compare efficiency + tolerability of atypical vs typical antipsychotics

P → systematic review of 232 studies involving various drug trials

F → atypical = more effective overall + lower patient attrition rates

C → atypical = more sustainable + effective treatment path

Psychological explanations to schizophrenia: cognitive explanations

• Focuses on role of IMP

• Dysfunctional thought processing:

  • Metarepresentation

  • Central control

Psychological explanations to schizophrenia: cognitive explanations → metarepresentation

Cognitive ability to reflect on thoughts + behaviours + identify them as internal

Dysfunction:

• Disrupt ability to recognise own thoughts + actions

• Thought insertion = belief thoughts are being projected into the mind by others

Psychological explanations to schizophrenia: cognitive explanations → central control

• Ability to suppress automatic responses while performing deliberate actions instead

Dysfunction:

• Cannot stop tangential thoughts from intruding into speech = word salad or derailment

• Disorganised speech + thought disorder = inability to suppress automatic thoughts

Psychological explanations to schizophrenia: cognitive explanations → Stirling study

Stirling et al

A → investigate central control in scz ppts

P → 30 scz ppts vs 18 non-scz ppts did range of cognitive tasks ~ stroop test

F → scz ppts took 2x to name ink colour + supress impulse of reading words

C → supports central control as proximate correlation in scz

C → does not provide evidence central control is cause

Psychological explanations to schizophrenia: cognitive explanations →

Psychological explanations to schizophrenia: family dysfunction

• Social stressor

• Maladaptive patterns of communication

• High levels of interpersonal conflict within home

• Primary environmental triggers → in combination with underlying genetic vulnerability

Psychological explanations to schizophrenia: family dysfunction → schizophrenogenic mother

• Fromm-Reichmann

• Schizophrenogenic mother → primary cause of paranoid delusions

• Schizophrenogenic mother = simultaneously cold + rejecting + overly controlling

• Creates climate of secrecy + tension → leads to profound distrust in developing child

• Child eventually breaks from reality → develops into paranoid delusion + schizophrenia

• Marital schism = psychological disturbance due to marital problems

Psychological explanations to schizophrenia: family dysfunction → double bind theory

• Bateson

• Explain disorganised thinking

  • Social withdrawal

• Double bind = communication paradox → person receives two or more conflicting messages

  • Verbally convey one message + non-verbally conveys opposite message

• Child cannot solve contradiction + fear punishment either way = become confused + lose grip on reality

Psychological explanations to schizophrenia: family dysfunction → expressed emotion (EE)

Psychological explanations to schizophrenia: family dysfunction → expressed emotion (EE) study

Vaughn and Leff

• Expressed emotion = measure of level of negative emotion directed toward patient by caregivers

• Three main elements → verbal criticism + hostility & rejection + emotional over-involvement

• 
  

Psychological explanations to schizophrenia: family dysfunction → Read et al

Read et al

• Reviewed 46 studies of child abuse + scz

• 69% of in-patients diagnosed with scz → had a history of abuse

Psychological explanations to schizophrenia: family dysfunction → Tienari

Psychological

Interactionist approach to schizophrenia

Combines biological + psychological + environmental factors → explain + treat schizophrenia

Holistic

Interactionist approach to schizophrenia: limitations of single explanations

• Biological → ~ half of MZ twins = discordant

  • Share genes yet not both have schizophrenia

• ????????????

Interactionist approach to schizophrenia: diathesis-stress model

• Inherit a vulnerability to scz ~ genetic risk, biological predisposition = diathesis

• Combined with environmental stressors = develop disorder → pushes person past the threshold

  • Environmental stressor ~ drug use + family conflict + traumatic life event

• Explains why MZ do not have a 100% concordance rate

Interactionist approach to schizophrenia: diathesis-stress model → Meehl

• Meehl’s model → original diathesis-stress model

• Diathesis = entirely genetic → result of single ‘schizogene’

• Meehl suggested no schizogene = no scz → even despite chronic stress

• Have schizogene + chronic stress in childhood ~ schizophrenogenic mother = develop scz

Interactionist approach to schizophrenia: diathesis-stress model → modern understanding

• No single ‘schizogene’ → range of biological factors + genetic predispositions

• Modern view of diathesis → also includes factors beyond genetic ~ psychological trauma

• Read → proposed neurodevelopmental model

  • Early trauma alters developing brain

  • Early + severe trauma ~ child abuse = seriously affect many aspects of brain development

  • Hypothalamic-pituitary-adrenal (HPA) → become over active = increases vulnerability to stress

Interactionist approach to schizophrenia: diathesis-stress model → Tienari

Interactionist approach to schizophrenia: modern understanding of stress

• Original diathesis-stress model → stress = psychological in nature ~ stress resulting from parenting

• Modern definition of stress = anything that risks triggering schizophrenia → Houston

• Cannabis as a stressor → increases risk of scz up to x7

  • Interferes with dopamine system

Interactionist approach to schizophrenia: treating scz

• Combining antipsychotic medication + psychological therapies → CBT

• Turkington → points out belief in biological causes of scz can co-exist with use of CBT to relieve psychological symptoms

•