Schizophrenia

What is Schizophrenia?

• mental disorder

How many people suffer with Schizophrenia?

• 1% of the world population

What age is Schizophrenia most commonly diagnosed at?

• between the ages of 15 and 35

How can the condition affect the sufferer?

• can affect a sufferer’s thought processes, physical functions and perception of reality

Explain the difference in sufferer’s symptoms

• some sufferers may only encounter symptoms sporadically

• whereas for others, these are more persistent

Explain positive symptoms of Schizophrenia

• symptoms in addition to normal functioning

What are the Positive Symptoms of Schizophrenia?

• Hallucinations

• Delusions

• Disorganised thinking

• Catatonic behaviour

Explain Hallucinations

• unusual perceptions of environment stimuli unique to the individual

• which no one else can perceive

• usually auditory (e.g. hearing voices)

• but may also be visual (e.g. seeing objects), olfactory (e.g. perceiving a disgusting smell) or tactile (e.g. feeling something or someone is touching the skin)

Explain Delusions

• irrational beliefs that seem real

• but are not true

• paranoid delusions involve a person believing they are being followed or spied upon

• delusions of grandeur involve exaggerated beliefs about one’s own abilities or importance (e.g. being famous or having superpowers)

Explain Negative Symptoms of Schizophrenia

• reduction in normal functioning

What are the Negative Symptoms of Schizophrenia?

• Speech poverty

• Avolition

• Affective flattening

• Social/Occupational dsyfunction

• Anhedonia

Explain Speech poverty

• significant reduction in amount or quality of what is spoken

• may involve reduced verbal fluency

• e.g. difficulty with saying a list of words for a given topic

• reduced language complexity

• e.g. short utterances

• or a notable delay in verbal responses during a conversation

Explain Avolition

• (or ‘apathy’)

• difficulty to begin and maintain goal directed behaviour

• involves significantly reduced self-motivation to take part in activities

• despite having opportunity to do so

• e.g. Choosing to sit on one’s bed for many hours rather than going to work which is a short walk away

Explain Co-morbidity

• when a person has two or more disorders at the same time

• for example, schizophrenia is often co-morbid with depression, substance abuse and OCD

• this can affect the diagnosis of schizophrenia

• cos it leads to uncertainty about whether different disorders are occurring independently or simultaneously

How does co-morbidity cause an inaccurate diagnosis of Schizophrenia?

• If a clinician does not recognise that a person has more than one condition

• they may provide an inaccurate diagnosis of a singular condition

• one reason for this is that one of the co-morbid disorders can cause symptoms of the other

• In this case, a person is likely to receive an inaccurate diagnosis of the secondary condition based on their current symptoms

• rather than a correct diagnosis of having both conditions co-morbidly

What are the limitations of co-morbidity?

• Evidence highlighting the issue of co-morbidity in diagnosis

• People with co-morbid schizophrenia are excluded from research

Evaluate the limitations of Evidence highlighting the issue of co-morbidity in diagnosis

• Evidence is provided by Buckley et al. (2009)

• they reported: 50% of schizophrenics had co-morbid depression, 47% substance abuse and 23% OCD

• could cause issues in diagnosis

• as one clinician may diagnose a patient with one disorder

• and another may diagnose the same patient with a different disorder

• and not recognise that the patient has co-morbidity

• co-morbidity can lead to low inter-rater reliability in diagnosis

• Furthermore, high levels of co-morbidity might also suggest that schizophrenia consists of distinct sub-types

• for example, schizophrenia with obsessive-compulsive symptoms may be one such sub-type which should be considered distinct from schizophrenia with substance abuse

Evidence People with co-morbid schizophrenia are excluded from research

• many schizophrenics are not recognised as having the disorder

• cos a clinician may diagnose a patient with their other co-morbid disorder such as bi-polar disorder and not recognise that they also have schizophrenia

• these patients may be excluded from research into schizophrenia

• meaning the diagnosis would be invalid

• and any research findings obtained may not represent sufferers of schizophrenia with prominent co-morbid disorder

How does culture bias affect the diagnosis of Schizophrenia?

• Culture bias concerns differential treatment of ethnic groups

• there is a tendency for certain ethnic minorities to be over-diagnosed with schizophrenia

• for example, people of Afro-Caribbean descent are several times more likely than white people to be diagnosed with schizophrenia when they are a minority group in society

What is one reason for differential diagnosis of Schizophrenia due to culture?

• certain ethnic groups may face stigma

• if they are diagnosed with a mental disorder

• this means they may not seek help in the early stages of schizophrenia

• so it escalates into a serious diagnosable condition

• which may otherwise have been avoided

What is another reason for differential diagnosis of Schizophrenia due to culture?

• diagnostic tools are typically created by people with certain cultural backgrounds

• white American in the case of the DSM

• if a person belongs to a culture that values spiritual experiences involving hearing voices

• they may be willing to share these with others

• a clinician from a different culture who uses the DSM to diagnose the patient

• may identify these experiences as a symptom of schizophrenia and provide a diagnosis

• whereas a clinician from the same culture may instead identify these experiences as a norm and not provide a diagnosis

• can result in low inter-rater reliability in diagnosis between clinicians with a different understanding of cultural norms

What is the strength and limitation of culture bias in Schizophrenia?

Strength:

• Ways to reduce cultural bias in diagnosis

Limitation:

• Evidence for cultural bias affecting reliability of diagnosis

Evaluate ‘ways to reduce cultural bias in diagnosis’ as a strength of culture bias in Schizophrenia

• To reduce chance of culture bias affecting diagnosis

• clinicians should be trained to understand how people from different cultures might present their symptoms

• standardised diagnostic questions could also be used during a clinical interview

• to ensure patients receive a reliable assessment

• regardless of cultural background of themselves or their clinician

Evaluate ‘Evidence for cultural bias affecting reliability of diagnosis’ as a limitation of culture bias in Schizophrenia

• Luhrmann et al. (2015) interviewed 60 adults (20 from Ghana, India and US) diagnosed with schizophrenia about the voices they heard

• Many Ghanaian and Indian participants reported positive experiences(e.g. the voices were ‘playful’)

• whereas not one American did (e.g. the voices were ‘hateful’)

• this implies that an Indian patient may be more likely to report hearing voices to a clinician

• and if the clinician is American and does not recognise this experience as a norm

• it may be viewed negatively and a symptom of schizophrenia

• and if the clinician is Indian, the experience may be viewed positively and not considered abnormal

• Cultural differences from the perspective of both the clinician and patient can therefore lead to low inter-rater reliability in diagnosis

How does gender bias affect the diagnosis of Schizophrenia?

• Gender bias refers to differential treatment or representation of males and females, based on stereotypes

• In the context of diagnosing schizophrenia, males are statistically more likely to be diagnosed than females

• However, this may misrepresent the true prevalence of the disorder for each sex

How are women treated by clinicians when they present symptoms?

• Despite both genders experiencing schizophrenia, females typically function better than males when suffering with symptoms such as avolition or they seek support before these worsen. If females present such symptoms to a clinician, it may be assumed that they will be able to cope, or that the symptoms are too mild to warrant an official diagnosis.

What are the limitations of gender bias when diagnosing Schizophrenia?

• Evidence that gender bias affects diagnosis

• Evidence for a biological basis for gender differences in diagnosis

Evaluate ‘Evidence that gender bias affects diagnosis’ as a limitation of gender bias when diagnosing Schizophrenia

• evidence for gender bias in diagnosis was investigated by Loring and Powell (1988)

• they randomly selected 290 psychiatrists

• and asked them to read information about two patients and diagnose them according to standard diagnostic criteria (DSM-III)

• When the patients were described as ‘male’ or no information about gender was given

• 56% of the psychiatrists gave a diagnosis of schizophrenia in each case, compared to only 20% when they were described as ‘female’

• this suggests when considering symptoms and prognosis, gender bias influences whether a diagnosis is provided

Evaluate ‘Evidence for a biological basis for gender differences in diagnosis’ as a limitation of gender bias when diagnosing Schizophrenia

• may be a biological reason why females are less likely to be diagnosed with schizophrenia

• Kulkarni et al. (2001) found female hormone oestradiol was effective in treating schizophrenia in women

• when used as an antipsychotic therapy

• suggests that female biology naturally helps them cope better with schizophrenic symptoms

• than males so they may be less inclined to seek a clinical consultation

• this suggests that biological differences between gender may lead to under diagnosis of females

• and a misrepresentation of prevalence across genders

Explain symptom overlap

• Symptom overlap occurs when a person has one disorder

• but the characteristics of the disorder are shared with another

• For example, schizophrenia and bipolar disorder are often characterised by the common symptom of depressed mood

How can symptom overlap lead to low inter-rater reliability between clinicians?

• cos if a person presents the symptom of depressed mood to different clinicians

• one clinician may identify this as a symptom of bipolar disorder

• whilst another may identify this as a symptom of schizophrenia

What are the limitations of symptom overlap in Schizophrenia?

• Evidence for symptom overlap affecting diagnosis

• Inappropriate medication is a negative consequence of low inter-rater reliability due to symptom overlap

Evaluate ‘Evidence for symptom overlap affecting diagnosis’ as a limitation of Schizophrenia

• Ellason and Ross (1995) gave 108 patients with a diagnosis of dissociative identity disorder (DID) the ‘Positive and Negative Syndrome Scale’

• They found that the patients reported more positive symptoms than schizophrenic patients typically experience

• The consequence for patients with DID is they are often provided with an invalid false-positive (type 1 error) diagnosis of schizophrenia

• cos clinicians more commonly associate the overlapping positive symptoms with schizophrenia rather than DID

Evaluate ‘Inappropriate medication is a negative consequence of low inter-rater reliability due to symptom overlap’ as a limitation of symptom overlap in Schizophrenia

• An implication of the issue of symptom overlap is that it can lead to misdiagnosis and consequently an incorrect therapy

• For example, a schizophrenic patient with depressed mood may be misdiagnosed with bipolar disorder

• and receive a prescription for this disorder

• This treatment may be ineffective and would also have negative economic implications for society

• One way to deal with this issue may be to examine the grey matter content of the brain

• as schizophrenics can experience a decrease of grey matter, while bipolar sufferers do not

• This shows how objective, empirical evidence can support a more unreliable diagnosis of schizophrenia based on symptoms alone

Explain what the genetic basis of schizophrenia suggests about biological characteristics

• inherited from parents

• faulty version of gene occurs due to random mutation

• but can then be inherited by offspring

Explain and give an example of the candidate gene that has been identified that contributes to the risk of developing schizophrenia

• an example candidate gene is COMT gene

• located on chromosome 22

• controls an enzyme that breaks down dopamine

• if person inherits a low activity variant of the COMT gene

• enzyme is less effective

• so dopamine levels are allowed to increase

• excessive dopamine activity has been linked to hallucinations

• a symptom experienced by some schizophrenic patients

What does the polygenetic explanation propose that symptoms of schizophrenia are a result of?

• complex combination of many candidate genes

• no single gene is responsible

Explain twin studies as a way of investigating the genetic basis of schizophrenia

• Twin studies involve large samples of monozygotic (identical) twins and dizygotic (non-identical) twins

• when one of the twins has been diagnosed with schizophrenia

• Concordance rates are calculated separately for MZ and DZ samples,

• which is the number of twins within each sample who both have the disorder

• usually represented as a percentage

• If concordance rate is significantly higher for MZ twins than for DZ twins

• this suggests schizophrenia has a genetic basis because MZ twins share 100% of their genetic material

• whereas DZ twins share approximately 50%

• Gottesman (1991) reviewed over 40 twin studies and found the average concordance was 48% for MZ twins and 17% for DZ twins

• which suggests schizophrenia is at least partly genetic

What are the strengths and limitations of the Genetic basis of Schizophrenia

Strength:

• Adoption studies provide evidence for the genetic basis of schizophrenia

Limitation:

• Twin studies provide conflicting evidence for the role of genes

• Adoption studies provide evidence for the genetic basis of schizophrenia

• Purely genetic explanations are overly deterministic

Evaluate the ‘Adoption studies provide evidence for the genetic basis of schizophrenia’ as a strength of the genetic basis of schizophrenia

• Tienari et al.’s (2000) Finnish adoption study provides additional support for the genetic basis of schizophrenia. They found that 7% of the adopted children with schizophrenic mothers were diagnosed with the disorder, whereas only 2% of the adopted children with non-schizophrenic mothers received a diagnosis. Although both percentages were small, the prevalence of schizophrenia is 3 times higher for the children with a biological mother with the schizophrenia. Furthermore, this is convincing evidence because the related individuals lived apart so the similarity in symptoms is less likely to be due to living in the same environment and is a more valid way of measuring the influence of genes on schizophrenia.

Evaluate ‘Twin studies provide conflicting evidence for the role of genes’ as a limitation of the genetic basis of schizophrenia

Joseph (2004) conducted a meta-analysis of all twin study data prior to 2001. This reported a MZ twin concordance rate of 40% compared to 7% for DZ twins. Since MZ twins are genetically identical and the concordance rate is significantly higher compared to DZ twins, this strongly supports the role of genes in schizophrenia. However, because the concordance rate for MZ twins was not close to 100%, this suggests schizophrenia is not purely genetic. Overall, the findings indicate that although genetics are strongly involved in schizophrenia they are not the sole cause of the disorder and that other factors may be involved.

Evaluate ‘Methodological criticism of investigating genes in cohabiting family members’ as a limitation of the genetic basis of schizophrenia

A methodological issue of investigating concordance rates between family members living together is the fact that they are often affected by similar environmental influences. For example, siblings of a similar age may experience a similar level of overprotection from their parents and lead them to both develop social withdrawal, which is a symptom of schizophrenia. The regularly reported high concordance rates for schizophrenia between related individuals could therefore be due to exposure to family dysfunction and not genes. It is difficult to disentangle the comparative influences of heredity and environment because both factors affect individuals throughout their lifetime. This reduces the validity of research into the genetic basis of schizophrenia because environmental factors confound the results.

Evaluate ‘Purely genetic explanations are overly deterministic’ as a limitation of the genetic basis of schizophrenia

An additional limitation of the genetic explanation is it is overly deterministic to assume that a child that who inherits a particular combination of genes will suffer from schizophrenia. Genes may predispose an individual to develop the biology that makes them vulnerable to the disorder; however, they may demonstrate free will by making particular life choices that means they encounter environmental situations that mitigate any potential innate factors. For example, if a child is aware that one of their parents has schizophrenia, they may choose to begin therapy at the onset of schizophrenic symptoms which prevents the disorder from developing

What is dopamine?

• a neurotransmitter

• which has many functions in the brain

Explain what the dopamine hypothesis suggests

• suggests that abnormalities in dopamine systems

• involved in movement and attention are responsible

Explain hyperdopaminergia

• increase in dopamine activity (hyperdopaminergia)

• in subcortex of brain

• has been linked to positive symptoms of schizophrenia

• One possible cause may be presence of abnormally high levels of D2 receptors on receiving neurons results in more dopamine binding and therefore more neurons firing

• If this increased activity occurs in Broca’s area (responsible for speech production) this could lead to auditory hallucinations

• and additions to speech (such as word salad) which are symptoms of paranoid and disorganised schizophrenia

Explain hypodopaminergia

• decrease in dopamine activity (hypodopaminergia)

• in the cortex

• been linked to negative symptoms of schizophrenia

• Decreased activity in prefrontal cortex

• which is responsible for higher-order thinking

• can be linked to cognitive deficits (such as avolition) which impairs decision making

What are the strengths and limitations of the Dopamine Hypothesis of Schizophrenia?

Strengths:

• Supporting evidence for the dopamine hypothesis

• Pharmacological applications

Limitations:

• Inconclusive evidence for the dopamine hypothesis

• The dopamine hypothesis is reductionistic

Evaluate ‘Supporting evidence for the dopamine hypothesis’ as a strength of the Dopamine Hypothesis of Schizophrenia

A great deal of supporting evidence for the role of dopamine comes from studying the effects of drugs on the symptoms of schizophrenia. Typical antipsychotic drugs (such as chlorpromazine) have an antagonistic effect by blocking dopamine receptors. Thornley et al. (2003) reviewed 13 trials (1121 participants) and found that chlorpromazine was associated with better overall functioning and reduced symptom severity. This suggests that an abnormally high level of dopamine activity is linked to schizophrenia.

Evaluate ‘Pharmacological applications’ as a strength of the Dopamine Hypothesis of Schizophrenia

A strength of understanding the neurochemical processes involved in schizophrenia is the practical application of developing psychoactive drugs that alter levels of dopamine. For example, the theory that hallucinations may be caused by excessive dopamine activity has led to the development of antagonistic drugs that decrease these levels of activity and ultimately the symptoms of schizophrenia. Such applications can help individuals suffering with schizophrenia to have a better quality of life.

Evaluate ‘Inconclusive evidence for the dopamine hypothesis’ as a limitation of the Dopamine Hypothesis of Schizophrenia

The fact that other neurotransmitters may be involved in schizophrenia has led to the evidence for the role of dopamine being inconclusive. Noll (2009) claims antipsychotic drugs only help alleviate symptoms such as hallucinations in one-third of cases. Additionally, some people experience such symptoms despite having normal levels of dopamine activity. This suggests dopamine may be just one of many causal factors involved.

Evaluate ‘The dopamine hypothesis is reductionistic’ as a limitation of the Dopamine Hypothesis of Schizophrenia

A limitation of the dopamine hypothesis is that it can be criticised for over-simplifying the complex causes of schizophrenia down to the sole action of dopamine. Despite there being two aspects, which together consider the effects of increased and decreased levels of dopamine activity, there are many other neurotransmitters that have been implicated in the causes of schizophrenia other than just dopamine. For example, current research has shifted towards the role of glutamate. Furthermore, the presence of psychological factors can influence the extent to which levels of dopamine affect schizophrenic symptoms for an individual. A particular level of dopamine activity is therefore just one of a number of interacting factors and may not therefore be a complete explanation of schizophrenia.

What are neural correlates of schizophrenia?

• refers to abnormalities in structural or functional features of the brain

• which link to particular schizophrenic experiences

Explain reduced density and volume of grey matter

Reduced density and volume of grey matter (neuron cell bodies) in the left temporal lobe has been linked to the positive symptom of auditory hallucinations. The upper part of the temporal lobe (superior temporal gyrus) contains the auditory cortex which is involved in perceiving and interpreting speech-based information. Decreased connectivity affects the ability of an individual to realise that internally generated speech is their own ‘inner voice’ and misattribute this to someone else, giving rise to the experience of ‘hearing voices’

Explain enlarged ventricles

Enlarged ventricles (fluid-filled gaps between brain areas) increase in size because of shrinkage or damage to the surrounding brain matter. Enlarged ventricles in central brain areas and the prefrontal cortex have been linked to negative symptoms of schizophrenia such as cognitive deficits and avolition

What are the strengths and limitations of Neural Correlates of Schizophrenia?

Strengths:

• Research evidence for decreased volume of grey matter

• Research evidence for enlarged ventricles

• Research into neural correlates fulfils scientific criteria

Limitations:

• Correlation/causation problem

Evaluate ‘Research evidence for decreased volume of grey matter’ as a strength of Neural Correlates of Schizophrenia

Research evidence supporting the role of decreased grey matter volume of the temporal lobe in schizophrenia is provided by Milev et al. (2003). They performed MRI scans to measure temporal lobe tissue volume of 123 schizophrenics and conducted a correlational analysis in a 5-year longitudinal study. They found smaller temporal lobe grey matter volume was negatively correlated (as the volume of grey matter decreases, persistence of hallucinations increases) with persistence of hallucinations during follow-up, suggesting that hallucinations may have a neurological basis

Evaluate ‘Research evidence for enlarged ventricles’ as a strength of Neural Correlates of Schizophrenia

Research evidence supporting the role of enlarged ventricles in schizophrenia is provided by Ho et al. (2003). They conducted a longitudinal study of structural brain abnormalities using MRI in 73 schizophrenic patients and 23 controls. In a 3-year follow-up they found that negative symptom severity was positively correlated (as ventricles increase, negative symptom severity also increases) with enlargement in frontal lobe cerebrospinal fluid volume (Pearson r = 0.44; n = 70; p<0.001). These findings suggest a link between schizophrenic symptoms and neurological structures

Evaluate ‘Research into neural correlates fulfils scientific criteria’ as a strength of Neural Correlates of Schizophrenia

A strength of neural correlates as an explanation of schizophrenia is that the supporting evidence often fulfils the criteria of scientific research. In order to study structural and functional features of the brain, various imaging techniques, such as MRI and PET scans are used. These produce images which enable objective comparisons between schizophrenic and non-schizophrenic brains which are free from bias. However, these techniques are limited in that they do not show why the features developed, but merely if they are currently present or not. Therefore, used in isolation, brain scans cannot provide a full explanation of schizophrenia and casts doubt on whether solely scientific methods can be used

Evaluate ‘Correlation/causation problem’ as a limitation of Neural Correlates of Schizophrenia

A limitation of research into neural correlates is that is it difficult to establish causality. Many studies have found structural or functional abnormalities in individuals displaying symptoms of schizophrenia, but such correlational evidence does not show whether such abnormalities are a cause or consequence of having the disorder. For example, research may show that decreased volume of grey matter is linked to negative symptoms of schizophrenia; however, it is also possible that another factor is responsible for both the decrease in grey matter and the negative symptoms. Additionally, establishing if one factor causes another is problematic because individuals are investigated after the disorder has been diagnosed so the initial cause of schizophrenia is impossible to establish

What do the family dysfunction explanations of schizophrenia suggest?

• symptoms are a result of problematic communication patterns and relationships within a family

• A challenging family environment can make an individual vulnerable to developing the disorder

Explain double-bind communication

• involves contradictory verbal or non-verbal messages being expressed

• usually by a parent towards a child

• child may feel trapped cos they fear that by responding to one of the messages they will fail to act on the other

What can the Double-bind communication patterns prevent the development of?

• prevent development of internally coherent construction of reality

• cause the world doesn’t seem to make sense

• and in long-term can lead to typically negative symptoms of schizophrenia

• such as flat affect (lack of a normal range of feelings and behaviours), disorganised thinking and avolition

• in order to escape double-bind situations

Give an example of double-bind communication

• For example, a child says something embarrassing during a family meal and their parent shouts

• “You never know how to act properly around other people. Go to your room!”

• This could cause internal conflict

• cause child cannot improve their social skills whilst confined to their room

• They display the schizophrenic symptom of social withdrawal to try to avoid such situations in future

• cause for fear of saying something wrong