schizophrenia Flashcards
ICD
21 chapters, in which only one chapter is dedicated to mental health.
DSM
Produced by the American Psychiatric Association and is the dominant manual in the US (also used elsewhere). The DSM classifications have to be used in the US to make diagnosis. The most recent edition is the DSM 5 (2013).
The main goals of the DSM 5
assist clinicians
identify treatment
to provide better care for patients.
Why is the DSM revised
discovery of new disorders
improving consistency of diagnosis
for a greater understanding of already known disorders.
Why s the DSM 5 better than DSM 4
breaks downs into more specific categories so they can be better treated. It is more precise.
5 Diagnostic Criteria from DSM-5
dellusions hallucinations disorganised thinking (speech) grossly disorganised/catatonic behaviour negative symptoms
describe delusions
fixed false beliefs resistant to change despite contrary evidence. May be thought withdrawal, thought insertion or delusions of control. (positive symptom)
describe hallucinations
Perception-like experiences with no external stimulus. Often auditory but could be other senses; smell or sight. (positive symptom)
describe disorganised thinking (speech)
Disorganised thought shown through speech. Involves switching topics illogically, irrelevance and incoherence. (positive symptom)
describe grossly disorganised/catatonic behaviour
Unpredictable behaviour. Catatonic refers to decrease in reactivity to the environment, i.e. rigid posture, lack of verbal or motor responses. (positive symptom)
describe negative symptoms
Reduced emotional expression- lack of eye contact, facial expressions, body language. Avolition: decrease in motivation and self-initiated purposeful actions. (Level of functioning in one or more major areas i.e. work, personal relations or self-care must have diminished for diagnosis)
type 1 schizophrenia
Positive symptoms
In some way adding to the sufferer’s personality
type 2 schizophrenia
Negative symptoms
Taking away from the sufferer’s personality
Reliability of Diagnosis (5 points)
- How do clinicians diagnose patients with an illness?
- Reliability is necessary but not sufficient for validity of diagnosis as consistent diagnoses may still all be incorrect.
- Inconsistent classification systems could lead to unreliable diagnosis as they will create different diagnoses for the same patients.
- Inter-rater reliability: Clinicians all reaching the same diagnosis- consistency of diagnoses.
Validity of Diagnosis
How is schizophrenia and its symptoms defined?
There is no physical sign characterises schizophrenia, diagnoses relies on observation of speech and behaviour.
The disorder has to be meaningfully classified - this is asses in three ways:
-descriptive validity
-aetiological validity
-predictive validity
descriptive validity
Are the symptoms right?
Defining medical illness through symptoms.
Patients with very different symptoms can all be diagnosed with schizophrenia i.g. type 1 and type 2 symptoms.
It may be better to treat all symptoms separately instead of the vague label of schizophrenia.
aetiological validity
Can mechanisms/causes be identified?
You can argue an illness is well defined if using evidence from causes and mechanisms.
predictive validity
What is the prognosis/reaction to treatment?
How the illness has progressed over time and predict how they react to treatments.
3 issues in classification of diagnosis
- Reliability is necessary but not sufficient for a diagnosis to be valid – consistent diagnoses might all be consistently incorrect.
- Inconsistent classification systems may lead to unreliable diagnosis as different classification may not give the same diagnosis – differences for the same people (not valid due to unreliability)
- We gain reliable diagnoses when two or more clinicians give the same diagnosis (inter-rater reliability)
3 factors affecting reliability of diagnosis
Differences in procedures (e.g. use of classification systems)
Differences between clinicians; subjective interpretation
Difference between patients
Elaborate on Differences in procedures (e.g. use of classification systems) (4 points)
- If different clinicians use different classification systems, they are likely to make different diagnoses.
- Was a problem in the past because doctors used different diagnostic criteria in different parts of the world (DSM is dominant in US)
- Cooper (1972) : American clinicians diagnosed SZ twice as often and British clinicians diagnosed mania and depression twice as often when shown the same video clip.
- ICD allows diagnosis with symptoms within the last month, but DSM-5 insists on some symptoms being present for 6 months
Elaborate on Differences between clinicians; subjective interpretation (2 points)
- Even if the same classification systems are being used, clinicians may interpret what they say differently.
- example: DSM-5 states that delusions must be ‘bizarre’, which is a subjective phrase
Elaborate on Difference between patients (3 points)
- Patients may act differently on different days, or differently to different doctors (empathy, warmth, friendliness, professionalism, gender, age, ethnicity)
- It depends on their mood and the variability of their symptoms
- This means a diagnosis could be different on different days
Improvements in reliability over time (2 studies)
Beck (1967) found that the inter-rater reliability between two psychiatrists diagnosing 154 patients was only 54%.
Cooper (1972) also found poor agreement between US and UK clinicians.
These two studies are dated and studied DSM-2, which was much weaker than subsequent editions – it was much vaguer and this meant that low reliability was likely.
Reliability improved with DSM-3 (1980) by removing the vague descriptions and clarifying how many and which symptoms were needed for a diagnosis.
Studies found that consistency for the diagnosis of SZ increased to 81%, which suggests an improved from DSM-2.
what makes a diagnosis valid
- Reliably defined/classified and diagnosed
2. Validly defined or classified
Brief outline of the genetic explanation
We inherit 50% of our genes from each parent. Genes are chemical ‘codes’ for construction of cells, including those in the brain.
The Brain is the source of all mental states therefore impacting disorders of mental state (schizophrenia).
If genes determine brain structure then we will inherit psychological traits- schizophrenia may be heritable.
liability threshold model
The idea that schizophrenia is not the result of a single gene or even that a combination of genes is the sole cause of schizophrenia. The more schizophrenia related genes you have the greater your chance of developing it.
molecular genetics
The link between specific genes and schizophrenia.
molecular genetics (Glatt et al)
association between the dopamine D2 receptor gene and schizophrenia. (30% increased chance)
Gottessman review
Based on 40 studies. Compared MZ twins reared together (concordance rate=48%), MZ twins reared apart (concordance rate= 58%), DZ twins reared together (concordance rate 17%).
Kendler
MZ twins reared together (concordance rate=53%), DZ twins reared together (concordance rate=15%)
Cardno
MZ twins reared together (concordance rate=50%), DZ twins reared together (concordance rate=4.1%)
Summary of twin studies
MZ twins have significantly higher concordance rates.
The more genes twins share the higher the concordance rate.
How does Gottessman support the genetic explanation
MZ twins separated at birth is higher than those reared in the same environment which provides strong evidence for the genetic explanation as it was not environmental factors that caused onset of schizophrenia.
Tienari
(Finland) Adopted children of schizophrenic mothers had a 7% chance of developing schizophrenia compared to a control group (adopted children with non-schizophrenic mothers) who had a 1.5% chance.
Wahlberg
Reevaluated Tienari, found environmental factors had significant impact in the development of schizophrenia (families with poor communication)
Kety
(Denmark) High rates of schizophrenia found in adopted children whose biological mothers had schizophrenia even if adopted by ‘healthy’ parents.
general trend in adoption studies
The general trend suggests that biological children of schizophrenic parents are at greater risk of developing the disorder. This suggests genetics have significant impact in development of schizophrenia.
methodological issues in adoption studies (2)
- Adoptive parents likely to be aware of mental illness in biological parents. This means these children are at greater risk of being in psychologically harmful environments as better informed parents may not adopt these children.
- Therefore similarities between biological mothers and their children is better explained by environment.
summary of the dopamine hypothesis
Biochemical abnormalities causing schizophrenia-a result of over-activity in parts of the brain controlled by dopamine.
limbic system summary
limbic system –> dopamine (neurotransmitter) –> regulates emotion