Paper 3: Schizophrenia Flashcards
(77 cards)
- Classification and diagnosis of Schizophernia
define schizophrenia and what aspects of
functioning are affected by schizophrenia?
-Schizophrenia is a severe mental disorder characterised by a profound disconnection from reality, involving a disruption of cognition and emotion
-It affects a person’s language, thought, perception and even their sense of self
- Classification and diagnosis of Schizophrenia
At what age is
schizophrenia typically diagnosed and who is more commonly affected?
- most often diagnosed between the ages of 15-35
- more commonly diagnosed in men, in cities and in the working class population
- Schizophrenia ranks among the top 10 causes of disability worldwide and affects about 1% of the population at some point in their lives (Mathers et al., 1996)
- Classification and diagnosis of Schizophernia
What is the difference between positive symptoms and negative symptoms?
- Positive = atypical symptoms experienced in addition to normal experiences e.g. hallucinations and delusions
delusions:
- delusions of grandeur
- paranoid/persecutory delusions
- delusions of reference
- Negative = atypical symptoms that represent a loss to normal experiences e.g. speech poverty (alogia) and avolition (apathy)
- Classification and diagnosis of Schizophernia
How is schizophrenia
diagnosed, and why is this problematic?
- it does not have one defining characteristic
- This is true of all psychiatric disorders: there are no reliable diagnostic biomarkers of differential diagnosis (comparing to other illnesses) or prognosis (response to treatment)
- Diagnosis is done through interview and observation and is therefore subjective - this differs from physical illness which is measured objectively e.g. blood tests, x-rays
- In addition the ICD-11 and DSM-5 differ in their diagnosis
- Classification and diagnosis of Schizophernia
Which symptoms are required for an ICD-10 based diagnosis of schizophrenia and for how long and what are positive symptoms required for ICD-10 diagnosis?
- two or more negative symptoms for one month (i.e. positive symptoms are not required).
The ICD-10 also recognised a range of subtypes of SZ:
- Paranoid (powerful delusions and hallucinations but few other symptoms)
- Hebrephrenic - involves primarily negative symptoms
- Catatonic - involves disturbance to movement
- Classification and diagnosis of Schizophernia
Which symptoms are required for a diagnosis of schizophrenia using DSM-V and for how long and what are the additional criteria?
Two or more of the following for at least a one-month (or longer) and at least one of them must be positive symptoms (1, 2, or 3):
1. Delusions
2. Hallucinations
3. Disorganized speech
4. Grossly disorganized or catatonic behavior
5. Negative symptoms, such as diminished emotional expression
- Classification and diagnosis of Schizophernia
What are the main
differences between ICD-
10 and DSM-V and what is the impact of the differences in the classification systems?
Similarities: Both classify schizophrenia as a psychotic disorder, consider cultural factors, and are widely used internationally.
Differences: They vary in subtypes, symptom duration, emphasis on negative symptoms, and the handling of schizoaffective disorder.
- Classification and diagnosis of Schizophernia
How do the terms reliability and validity apply to schizophrenia?
- Reliability refers to the consistency of the diagnostic instrument to assess the severity of the schizophrenic symptoms.
- Validity refers to the extent that a diagnosis represents something that is real and distinct from other disorders and the extent that a classification system such as ICD-10 or DSM-5 measures what it claims to measure.
- Reliability and validity are linked - a diagnosis cannot be valid if it is not reliable.
- Classification and diagnosis of Schizophernia
What issues are there with the reliability of the
diagnosis of schizophrena?
Describe a research study that has investigated reliability of diagnosis in schizophrenia, and what
were the findings/ implications?
Reliability: the extent to which the diagnosis of SZ is consistent - the level of agreement between psychiatrists and diagnostic tools over time.
- It is the extent to which psychiatrists can agree on the same diagnosis when independently assessing patients (inter-rater reliability). In order for a classification system to be reliable, the same diagnosis should be made each time. Therefore different psychiatrists should reach the same decision when assessing a patient.
- The same diagnostic tool should also assess patients with the same diagnosis over a period of time (test-retest reliability).
- Classification and diagnosis of Schizophernia
what’s co-morbidity
co-morbidity is where two conditions co-exist in the same individual at the same
time
* a person with sz might also at the same time be suffering from
another condition, e.g. personality disorder, depression, alcoholism
- Classification and diagnosis of Schizophernia
8/16 markers that’s not come up before:
evaluate the reliability and validity in diagnosis and classification of sz
P: its high reliability when using standardized diagnostic instruments.
Eg: Osorio et al. (2019) found excellent inter-rater reliability using the DSM-5, with a kappa score of 0.97.
E: shows that when psychiatrists consistently apply standardized criteria, such as the DSM-5, they can reliably diagnose sz across different cases, ensuring appropriate treatment and improving prognosis.
C: high reliability does not guarantee validity; psychiatrists may agree on a diagnosis that does not accurately reflect the underlying condition, highlighting the need for more research into schizophrenia’s biological and psychological markers.
L: Overall, the use of standardised tools plays a critical role in improving diagnostic accuracy and consistency.
P: A limitation of schizophrenia diagnosis is its lack of inter-rater reliability.
E: Cheniaux et al. (2009) had two psychiatrists independently diagnose 100 patients using the ICD and DSM criteria. One diagnosed 26 with DSM and 44 with ICD, while the other diagnosed 13 with DSM and 24 with ICD.
E: This inconsistency shows that the diagnosis of schizophrenia can vary depending on the psychiatrist, reducing its reliability and potentially leading to misdiagnosis and inappropriate treatment.
L: This undermines the validity and reliability of the diagnostic process.
P: Another limitation is the issue of symptom overlap, which reduces diagnostic validity.
E: Lichtenstein et al. (2009) found that schizophrenia and bipolar disorder share genetic causes, suggesting biological similarities.
E: This overlap can lead to different diagnoses under different classification systems, such as schizophrenia under ICD and bipolar disorder under DSM, highlighting inconsistencies.
L: This reduces the validity of diagnosis and limits the reliability of classification systems in accurately differentiating between disorders.
- Biological explanations of SZ
Is schizophrenia an inherited disorder?
What were Gottesman’s
(1991) findings?
People do not inherit schizophrenia, but they inherit a genetic predisposition (vulnerability) to the disorder.
Gottesman (1991) carried out a family study and found the concordance rates for SZ:
- MZ twins: 48%
- DZ twins: 17%
- siblings: 9%
The results show that the closer the degree of genetic relatedness, the greater the risk of developing sz.
- Biological explanations of SZ
What does it means to say that schizophrenia is polygenic?
What is the role of genetics in the aetiology of schizophrenia?
What were the findings by Ripke et al. (2014)
many genes are involved, and a polygenic risk factor is calculated. Each individual gene presents a small increased risk of SZ.
Different combinations of these genes can lead to SZ. It is therefore aetiologically (caused) heterogeneous (by different things).
Ripke et al. (2014) studied 37,000 patients and found 108 separate genetic variations associated with increased of Schizophrenia.
- Biological explanations of SZ
Why are adoption studies helpful in determining the aetiological role of genetics?
What were the findings of Tienari et al. (2000)?
Adoption studies are very useful for disentangling shared genes from the same environment.
Tienari et al (2000) carried out an adoption study in Finland. Of the 164 adoptees whose biological mothers had sz 6.7% also were diagnosed compared to 2% of the 197 control group (no sz mother).
This is support for a genetic explanation for sz, but only that it increases the likelihood of developing sz.
- Biological explanations of SZ
strength of the genetic arguments as explanations of SZ
P: A strength of the genetic argument for schizophrenia is the clear link between genetic relatedness and risk of developing the disorder.
E: Gottesman (1991) showed that the closer the genetic relatedness, the greater the risk. Adoption studies, like Tienari et al. (2004), show that children of schizophrenia sufferers are at higher risk, even in families with no history of the disorder.
E: This supports the idea that genetic factors increase susceptibility to schizophrenia, emphasizing the role of biological inheritance.
C: However, genetics alone may not account for all cases, as environmental factors, such as stress or family dynamics, may also contribute.
L: This supports genetics’ involvement but suggests a diathesis-stress model, where genetic predisposition interacts with environmental factors to trigger the disorder.
- Biological explanations of SZ
limitation of the genetic arguments as an explanation of SZ
P: A limitation of the genetic argument for schizophrenia is the difficulty in separating the effects of nature and nurture.
E: Family and twin studies often investigate individuals who share similar environments, potentially inflating concordance rates regardless of genetic influence.
E: For example, high concordance rates in MZ twins could be due to their similar treatment, not just shared genetics. Even MZ twins reared apart still share the same prenatal environment, which may further contribute to their similarities.
C: This shared environment acts as a confounding variable, making it difficult to determine the relative influence of genetics and environment on the development of schizophrenia.
L: Therefore, the inability to disentangle nature from nurture reduces the validity of genetic explanations, as environmental factors may play a larger role than initially thought.
- Biological explanations of SZ
What is the dopamine hypothesis of schizophrenia?
What is hyperdopaminergia, in where is thought to occur in the brain in patients with schizophrenia?
- The original dopamine hypothesis stated that schizophrenia was caused by excessive activity of dopamine in the subcortex.
- This causes the neurons that respond to dopamine to fire too often and transmit too many messages. This message ‘overload’ may produce many symptoms of schizophrenia
- hyperdopaminergia is high levels of dopamine in subcortical areas projecting to Broca’s area may be associated with the experience of auditory hallucinations and/or speech poverty
- It is now thought people with sz have high numbers of D2 receptors
- Biological explanations of SZ
What is the updated dopamine hypothesis
How does Goldman-Rakic’s
(2004) work revise the dopamine hypothesis?
The more recent version of the dopamine hypothesis focuses on abnormal dopamine systems in the cortex - also focuses on hypodopaminergia
- Goldman-Rakic et al (2004) have identified low levels of dopamine in the prefrontal cortex in the negative symptoms of sz such as avolition. The prefrontal cortex is responsible for thinking and decision making.
- Biological explanations of SZ
explain the main 2 dopamine pathways associated with SZ
- Mesolimbic Pathway:
- Originates in the ventral tegmental area (VTA) and projects to the nucleus accumbens (NAc), where dopamine drives pleasure and reward.
- Stimulation of the NAc is essential for maintaining daily activities, but overstimulation can increase dopaminergic activity, leading to euphoria, dependence, and cravings.
- Hyperactivity of dopamine in this pathway is linked to the positive symptoms of schizophrenia (hallucinations, delusions), which are alleviated by antipsychotics (D2 antagonists).
- Overstimulation leads to positive symptoms. - Mesocortical Pathway:
- Dopaminergic projections from the VTA to the prefrontal cortex (PFC), which is involved in cognition, working memory, and decision-making.
- Dysfunction in this pathway leads to cognitive issues like poor concentration and decision-making.
- Medications like amphetamines can increase dopamine in the mesocortical pathway, enhancing cognition and activity in the PFC (e.g., Ritalin for ADHD works through this mechanism).
- Low dopamine levels in this pathway are thought to underlie the negative symptoms of schizophrenia.
- Dysfunction leads to negative and cognitive symptoms.
- Biological explanations of SZ
How is hypo- and hyper-dopaminergia thought to
relate to different symptoms of schizophrenia?
It may be that both hyperdopaminergia and hypodopaminergia are correct explanations - both high and low levels of dopamine in different brain regions are involved in SZ.
- Biological explanations of SZ
a strength and limitation of the dopamine hypothesis as a biological explanation of SZ
P: A strength of the dopamine hypothesis is that it provides an explanatory framework for positive symptoms of schizophrenia.
Eg: Kapur (2000) proposed the salience hypothesis, suggesting that dopamine abnormalities cause patients to attribute abnormal significance to otherwise neutral events. Dopamine, which normally codes salient environmental events, fires chaotically in schizophrenia, leading to delusional ideation as an attempt to reconcile this.
Ex: This suggests that delusions result from aberrant learning signals caused by dopamine dysfunction.
L: Therefore, the salience hypothesis bridges biological and clinical observations, enhancing its validity.
P: A limitation of the dopamine hypothesis is that it is supported by mixed evidence.
Eg: Amphetamines, which increase dopamine, can worsen schizophrenia symptoms or induce similar symptoms in non-sufferers. Antipsychotics, which reduce dopamine, alleviate symptoms in patients.
Ex: However, Moncrieff (2009) argues that dopamine levels are influenced by factors like stress and smoking, and research by Ripke et al. suggests that other neurotransmitters, like glutamate, also play a significant role. Recent studies using ketamine (a glutamate blocker) and investigating THC support this view.
L: This suggests dopamine may contribute to schizophrenia but is not the sole factor. A more comprehensive understanding likely involves multiple interacting neurotransmitters, undermining the validity of a purely dopaminergic explanation.
- Biological explanations of SZ
What does the ‘neural correlates’ of something mean?
Give an example of the neural correlates of schizophrenia
neural correlates refers to measurements of the structure or function of the brain that correlate with an experience. Both positive and negative symptoms have neural correlates.
- Enlarged ventricles and negative symptoms
- Ventral striatal activity and negative symptoms
- Superior temporal activity and positive symptoms
- Biological explanations of SZ
Describe how the study by Juckel et al. (2006) on the neural correlates of negative symptoms
Juckel et al. (2006) found a negative correlation between ventral striatum activity and overall negative symptoms of SZ.
The ventral striatum is part of the brain that is involved in the reward pathway. Loss of motivation (avolition) may be explained by low activity levels in this part of the brain.
- Biological explanations of SZ
Describe the work by Allen et al. (2007) on the neural correlates of hallucinations
The superior temporal gyrus consists of the auditory cortex. Allen et al (2007) found that patients experiencing auditory hallucinations recorded lower activation levels in the superior temporal gyrus and anterior cingulate gyrus. Therefore we can say that reduced activity in these two areas of the brain is a neural correlate of auditory hallucinations.