Psychopathology: Schizophrenia UNIT 4: PSYA4 [email protected] Topic Content In relation to their chosen disorder: 1. 2. 3. 4. Schizophrenia Depression Phobic disorders OCD Candidates should be familiar with the following: Clinical characteristics of the chosen disorder. Issues surrounding the classification and diagnosis of their chosen disorder, including reliability and validity. Biological explanations of their chosen disorder, for example, genetics, biochemistry. Psychological explanations of their chosen disorder, for example, behavioural, cognitive, psychodynamic and socio-cultural. Biological therapies for their chosen disorder, including their evaluation in terms of appropriateness and effectiveness. Psychological therapies for their chosen disorder, for example, behavioural, psychodynamic and cognitivebehavioural, including their evaluation in terms of appropriateness and effectiveness. Family Studies Gottesman (1991) carried out a meta-analysis and reviewed 40 studies that had investigated family history of schizophrenia. He found that the closer the degree of geneticrelatedness, the greater the risk of schizophrenia. Children with two schizophrenic parents have a concordance rate of 46%, children of one schizophrenic parent 16% and siblings 8%. This supports the genetic hypothesis of schizophrenia because… Twin studies Gottesman (1991) carried out a meta-analysis and reviewed 40 studies that had investigated family history of schizophrenia. Found a concordance rate of 48% for MZ twins and 17% for DZ twins. Problems? If there is solely a genetic cause for schizophrenia, the concordance rate for MZ twins would be 100%, and it isn’t (48%). Therefore genetics cannot offer a complete explanation for schizophrenia. Problems considered… It could be that the 48% concordance rate in MZ twins is not because they share 100% genes but because they share very similar experiences in life. For example, they look the same, may dress the same, may be treated the same and reacted to in the same way by others around them. Therefore it could be environmental factors that cause the schizophrenia rather than genetics. Evaluation (A02) Twins are very rare in the general population and so is schizophrenia. Therefore it is unusual to find twins with schizophrenia. This means that the samples studied are small and therefore limits the findings (i.e. may not be a true reflection of actual concordance rates). Adoptive Studies Kety et al (1988) studied 5483 Danish children who were adopted (who had a schizophrenic biological parent) between 1923-1947. A higher concordance rate (32%) for schizophrenia, or a related disorder (e.g. schizotypal personality disorder), was found for those who had been adopted and had a schizophrenic biological parent compared to a control group who had been adopted but didn’t have a schizophrenic biological parent. This suggests… Adoptive Studies However in this study the concordance rate of 32% included related disorders, not purely schizophrenia. Therefore this reduces the validity of the findings for a genetic basis of schizophrenia. Evaluation: The search for relevant genes The biological location of a specific gene for the cause of schizophrenia has not yet been identified, although several have been implicated in the development of the disorder. Therefore it is likely that multiple, interacting genes lead to schizophrenia. The search for a specific gene continues. IDA: Nature vs. Nurture Controversy surrounding origins of schizophrenia. Considerable evidence for genetic contribution. Environmental factors have also been shown to be important (more later). Most agree that schizophrenia arises from a combination of factors. Biochemical factors Biochemical abnormalities should be detectable in the brain of those diagnosed with SZ. The dopamine hypothesis SZ patients have excessive levels of dopamine in the brain. Biochemical Factors Drugs to treat schizophrenia: Phenothiazines Phenothiazines (neuroleptic, antipsychotic drugs), which work by reducing the action of dopamine (known as dopamine antagonists) can reduce the symptoms of SZ. This suggests that, because these drugs alleviate many of the symptoms of SZ, the case for dopamine being a significant contributory factor in the development of SZ is strengthened. Biochemical Factors Studies of drugs like amphetamines (dopamine agonists – enhance the actions of dopamine) have provided further support for the role of dopamine in SZ. Large doses of these drugs can induce positive symptoms very similar to SZ (e.g. hallucinations and delusions) in healthy individuals. This supports the suggestion that schizophrenia is due to an excess of dopamine in the brain. Randrup and Munkvad (1966) Observed behaviour similar to that found in those suffering from SZ in rats who were given amphetamines. The effects were then reversed by neuroleptic drugs (e.g. phenothiazines which work by reducing the action of dopamine). Post-mortems and PET scans 1. Excessive levels of dopamine. 2. Increased dopamine receptor density (more dopamine receptors tightly packed into the caudate nucleus putamen). Consequently, from the research using postmortems and PET scans, it is now thought that, rather than an excess of dopamine, schizophrenia is actually a result of overly sensitive dopamine receptors. Evaluation Neither post-mortems nor PET scans can reveal whether increased dopamine activity/increased dopamine receptor density causes schizophrenia or whether schizophrenia interferes with the dopaminergic system (problem of cause and effect). Evaluation Effectiveness of drug treatments Drugs that affect levels of dopamine do not benefit all sufferers of schizophrenia. Whilst many people recover fully after medication with dopamine-based drugs, others only partially respond and others show no effects at all. This suggests that a faulty dopamine system is not always a causal factor in schizophrenia and implicates other biochemical factors in the disorder. Evaluation continued… Effectiveness of drug treatments It may be that drugs work differently according to the type of SZ and the type of symptoms (i.e. positive or negative). E.g. amphetamines (known to affect dopamine activity) worsen positive symptoms and lessen negative symptoms of schizophrenia whereas phenothiazines alleviate positive symptoms but are not as effective with negative symptoms. IDA: Reductionist Biochemical explanation is reductionist. It reduces a complex behaviour such as schizophrenia down to a relatively simple level of explanation i.e. an imbalance in brain chemicals, specifically dopamine. Ignores all other potential influences in the course of this disorder, for example… Independent task In your booklets draw a visual representation of: - Drugs to treat schizophrenia: Phenothiazines 2. The use of amphetamines 3. Post-mortems and PET scans 1. Demonstrate what happens in terms of dopamine. Neuroanatomical Factors Research examining neuroanatomical factors that may play a role in the development of schizophrenia have used MRI (magnetic resonance imaging) scans. This is a non-invasive technique used to record radio waves from the brain. These recordings are computerised and assembled into a 3D image of the brain. Research Brown et al (1986) – found decreased brain weight and enlarged ventricles (which are the cavities in the brain that hold cerebrospinal fluid) in schizophrenic patients. Research Suddath et al (1990) used MRI to obtain images of brain structure from MZ twins in which only one twin had schizophrenia. The twin with schizophrenia had more enlarged ventricles than the twin without schizophrenia. The differences were so large that the twin with schizophrenia could be identified easily from the brain images in 12/15 twin pairs. Evaluation Humans do not have brains which are exactly the same size, weight and shape. Therefore it is not easy to measure ventricle enlargement accurately, and there are no set criteria for what constitutes enlargement. Ventricles enlarge naturally with age and are usually larger in male brains anyway. Therefore this limits the validity of the research and questions the role of structural abnormalities in the development of schizophrenia. Most MRI studies have been carried out on individuals already diagnosed with schizophrenia. A problem with this is that it is not clear whether structural abnormalities lead to schizophrenia or whether the development of schizophrenia causes structural changes – the problem of cause and effect. Pair task Exam Focus: June 2011 ‘There is considerable evidence that schizophrenia is caused by biological factors. These can be genetic, neuroanatomical, biochemical, viral or a combination of such factors.’4 Discuss biological explanations of schizophrenia. (8 marks + 16 marks) Plan your answer – use P.E.E.L for A02. Look at sentence starters in your booklet to help you… Colour-code Decide if the term belongs to the genetic, biochemical or neuroanatomical explanation of schizophrenia. Q&A!!!