Schizophrenia: Overview - PowerPoint PPT Presentation

Loading...

PPT – Schizophrenia: Overview PowerPoint presentation | free to download - id: f0fd8-YTY4N



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Schizophrenia: Overview

Description:

Psychosis is a syndrome (mixture of symptoms) delusions and ... Anhedonia ... OLIFE: Introvertive anhedonia (IntAnh); SPQ negative factor ... – PowerPoint PPT presentation

Number of Views:156
Avg rating:3.0/5.0
Slides: 41
Provided by: dralanpi
Learn more at: http://homepages.gold.ac.uk
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Schizophrenia: Overview


1
Schizophrenia Overview
  • Background
  • Schizophrenia symptoms/syndromes
  • Schizotypal personality
  • Dopamine hypotheses
  • Genetic effects on prefrontal functioning in SZ
  • Neurodevelopmental hypothesis
  • Neuropsychological accounts

2
Psychosis vs. Schizophrenia
  • Psychosis is a syndrome (mixture of symptoms)
    delusions and hallucinations
  • Psychotic disorders
  • schizophrenia
  • schizoaffective disorder
  • schizophreniform disorder
  • drug-induced psychoses
  • Other disorders have psychosis as an associated
    feature

3
Schizophrenia Basics
  • Most common psychotic illness
  • Affects 1 of population
  • costs billions p.a.
  • Definition
  • Must last gt6 months
  • incl. At least one month of halluc., delusions,
    grossly disorganised speech/behaviour
  • Can be very severe
  • 25-50 of patients attempt suicide

4
Delusions
  • Misrepresentations of perceptions or experience
  • Most common are persecutory
  • Others
  • referential somatic religious grandiose

5
Hallucinations
  • Disordered perception
  • perceptions without corresponding physical
    stimuli
  • Most commonly auditory
  • but can occur in any sensory modality

6
5 Symptom Dimensions in Schizophrenia
  • Positive symptoms
  • Negative Symptoms
  • Cognitive Symptoms
  • Anxiety and Depressive Symptoms
  • Aggressive Symptoms

7
Positive Symptoms
  • Additions to normal function
  • Delusions
  • Hallucinations
  • Distorted language/communication
  • Disorganised speech / behaviour
  • Catatonic behaviour
  • Agitation

8
Negative Symptoms
  • Losses of normal function
  • Affective flattening
  • Alogia
  • Avolition
  • Anhedonia
  • Attentional impairment
  • Blunted affect, emotional withdrawal, poor
    rapport, passivity, apathetic social withdrawal

9
Negative Symptoms
  • Different aetiologies
  • primary (a core feature)
  • secondary to-
  • ve symptoms
  • depression
  • extrapyramidal symptoms
  • environmental depreivation

10
Cognitive Symptoms
  • Thought disorder
  • Odd use of language
  • incoherence, loose associations, neologisms
  • Impaired attention / cognition
  • reduced verbal fluency
  • learning/memory
  • executive functions

11
Syndromes in Schizophrenia
  • Type 1 vs Type 2 (Crowe)
  • Liddles 3-syndromes scheme
  • reality distortion (positive)
  • psychomotor poverty (negative)
  • disorganisation

12
What Are Schizotypal Personality Traits?
  • Stable traits in healthy individuals
  • Tendencies to show features of behaviour/cognition
    that are qualitatively similar to those of
    schizophrenic patients
  • Underlying continuum model

13
Schizotypal Personality Multidimensionality
Schizotypal personality has 3 or 4 correlated
factors …
  • Positive schizotypy
  • Disorganised schizotypy
  • Negative schizotypy
  • 4th factor Impulsive nonconformity
  • Is this really schizotypal personality?

14
Schizotypal Personality Measures
  • Positive Schizotypy
  • OLIFE Unusual experiences (UnEx)
  • SPQ Cognitive-perceptual factor
  • Negative Schizotypy
  • OLIFE Introvertive anhedonia (IntAnh) SPQ
    negative factor
  • Disorganised Schizotypy
  • OLIFE Cognitive Disorganisation (CogDis) SPQ
    Disorganisation

15
Example OLIFE Items
  • Positive Schizotypy Measure Unusual
    Experiences (30 items)
  • -I have felt that I have special, almost
  • magical powers
  • -Do you ever feel that your thoughts
  • dont belong to you?
  • -Sometimes my thoughts are as real as
  • actual events in my life

16
SPQ Subscales
  • Positive (Cog-Perceptual)
  • Unusual perceptions odd beliefs
  • ideas of reference suspiciousness
  • Negative (Interpersonal)
  • No close friends excessive social anxiety
    constricted affect susp
  • Disorganised Schizotypy
  • Odd behaviour Odd Speech

17
Why Study Schizotypal Personality Traits?
  • Testbed for schizophrenia in readily-available,
    healthy individuals
  • Performance of high scorers should be similar to
    schizophrenics
  • Behaviour not contaminated by medication,
    illness, hospitalisation etc

18
More Reasons to Study Schizotypal Personality
Traits
  • May find specific associations with one
    schizotypal factor
  • Generates predictions for associations with
    specific SZ symptoms

19
Schizotypal Personality Traits and Psychosis
Proneness
  • Alternative definitions of schizotypy
  • -a prodrome for schizophrenia
  • -schizotypal personality disorder
  • -psychosis proneness
  • Follow-up studies of high-scoring subjects on
    schizotypal personlity traits

20
Schizotypal Personality Follow Up Studies
  • Kwapil, Chapman and Chapman
  • -10 year follow-ups
  • -small increase in Sz for positive schizotypy
    measures
  • -Follow-ups of high scorers on the ImpNon
    dimension did not show inc. Sz but small
    increases in other psychopathologies

21
Neuroscience of Schizophrenia
  • Dopamine and schizophrenia
  • Recent genetics advances
  • Neurodevelopmental hypothesis

22
Brain Dopamine Pathways
  • Nigrostriatal
  • degenerates in Parkinsons disease
  • Mesolimbic
  • positive symptoms of schizophrenia
  • Mesocortical
  • neg symptoms of schizophrenia
  • Tuberoinfundibular

23
Signals of reward availability
Addictive drugs opiates, cocaine, cannabis,
nicotine
Food/drink
EBS
Sex
Effective goal-directed behaviour
24
Evidence for DA Hypothesis
  • Stimulant drugs
  • -release DA
  • -amphet/cocaine abuse -gt paranoid
  • psychosis
  • Antipsychotic drugs
  • which are effective at treating positive
    symptoms are DA receptor (DR) blockers esp. D2 DR

25
Mesolimbic DA Hypothesis
  • Hyperactivity of mesolimbic DA mediates positive
    symptoms of psychosis
  • Accounts for these psychotic symptoms whether in
    SZ or other disorders

26
Mesocortical DA Hypothesis
  • Deficit of mesocortical DA mediates negative and
    cognitive symptoms of psychosis
  • - more controversial
  • - affects areas such as DLPFC
  • - degenerative in some SZ patients
  • - may be primary deficit
  • - may be secondary drug effect

27
New Developments in DA Hypotheses of SZ 1
  • Good recent review at-
  • http//www.acnp.org/g4/GN401000115/Default.htm

28
New Developments in DA Hypotheses of SZ 2
  • Recent advances in molecular genetics make it
    possibly to explore the effects of …
  • specific genetic polymorphisms
  • relevant to the DA hypothesis

29
Studies of the COMT gene
  • see Egan et al (2001).
  • Proceedings of the National Academy of Sciences
    (PNAS)
  • 98, 6917-6922

30
The COMT gene and SZ
  • Catechol-o-methyl transferase is a catabolic
    enzyme that degrades DA
  • The COMT gene has two variants which affect the
    functioning of the gene (val and met alleles)
  • The gene is on chromosome 22 close to regions
    which have been implicated in linkage studies
    with SZ
  • Family and association studies have implicated
    the COMT gene in SZ

31
Egan et al 2001 1
  • Argued that abnormal PFC function is a useful
    intermediate phenotype for SZ
  • Intermediate phenotypes are more likely to be
    related to gene function than the clinical
    diagnosis
  • SZ show reliable PFC disturbances on cognitive
    tests
  • So do healthy sibs inc. MZ co-twins

32
Egan et al 2001 2
  • DA plays role in modulating PFC during working
    memory (WM) tasks
  • As COMT gene affects prefrontal dopamine levels
    then may affaect WM
  • COMT knockout mice have increased DA in PFC and
    enhanced memory performance

33
Egan et al 2001 3
  • Measured WM and exec function using Wisconsin
    Card Sorting Test (WCST)
  • -WCST activates PFC
  • -DA-mimetic drugs improve WCST performance in SZ
  • Measured prefrontal neurophysiology using fMRI
    and the n-back WM task
  • -task activates DLPFC
  • -in SZ, and unaffected sibs, DLPFC activation is
    inefficient

34
Egan et al 2001 Results
Controls Sibs patients
35
Egan et al 2001 Results
  • fMRI during the n-back task showed, for patients
    and sibs, that DLPFC and ACC activation
    efficiency was affected by genotype-
  • val/val lt val/met lt met/met

36
Egan et al 2001 Results
  • Analysed 104 family trios (2 parents plus case)
  • In 126 gene transmissions from heterozygous
    parents to probands the val allele was
    transmitted 75 times (p0.03)
  • In unaffected sublings 77 val vs 87 met
    transmissions

37
The COMT gene and schizotypy
  • Various studies have shown that the COMT gene may
    be linked to schizotypal personality (Stefanis et
    al, 2002, 2004), although what aspects are not
    clear, with high schizotypy associated with
    presence of val allele

38
Neurodevelopmental Hypothesis of Schizophrenia
  • Proposes that Sz arises from ?genetic?
    abnormalities in fetal brain development
    (evidence?)
  • Why should such this give rise to peak incidence
    of Sz in teens and early 20s?
  • Ans Adolescent neural restructuring reveals
    earlier deficit (evidence?)
  • Maybe additional neurodegeneration during
    symptomatic phase of disease

39
Neuropsychological accounts of SZ
  • Usually propose a deficit in a specific cognitive
    process as responsible for a specific subset of
    SZ symptoms
  • Thus SZ perform worse/differently from controls
    on a cognitive task designed to measure the
    specific process

40
Neuropsychological accounts of SZ Examples
  • Latent Inhibition (Gray)
  • Negative Priming (various)
  • Contextual processing (various)
About PowerShow.com