- Created by: MajesticSue
- Created on: 05-04-17 08:44
Neural correlates: The dopamine hypothesis
The dopamine hypothesis claims that an excess of the neurotransmitter dopamine in certain regions of the brain is associated with the positive symptoms of schizophrenia.
Messages from neurons that transmit dopamine fire too easily or too often, leading to hallucinations or delusions. Schizophrenics have abnormally high numbers of D2 receptors on receiving neurons, resulting in more dopamine binding and so more neurons firing.
Drugs that increase dopaminergic activity
Amphetamine is a dopamine agonist as it stimulates nerve cells containing dopamine, causing the synapse to be flooded with dopamine. ‘Normal’ individuals who are exposed to large doses of dopamine-releasing drugs, e.g. amphetamine, can develop hallucinations and delusions.
Drugs that decrease dopaminergic activity
Many different types of antipsychotic drugs block the activity of dopamine in the brain; they reduce the activity of neural pathways that use dopamine as the neurotransmitter and so eliminate symptoms, like hallucinations and delusions.
The revised dopamine hypothesis
Davis and Kahn (1991) proposed that the positive symptoms of schizophrenia are due to an excess of dopamine in subcortical areas of the brain, in particular the mesolimbic pathway. The negative symptoms are caused by a deficit of dopamine in areas of the prefrontal cortex.
Cognitive behavioural therapy for psychosis (CBTp)
Delusions are due to faulty interpretations of events so CBTp helps to identify and correct these faulty interpretations.
Patients are encouraged to trace back the origins of their symptoms to understand better how they developed.
Encouraged to evaluate the content of their delusions or of their voices and test the validity of these beliefs.
They are set behavioural assignments so that they improve their general level of functioning.
- Schizophrenic patients can learn maladaptive responses to life’s problems due to their distorted thinking or the person struggling to assess cause and effect (e.g. thinking that something bad has happened because they wished it). In CBTp, the therapist has the patient develop their own alternatives to these previous maladaptive beliefs.
A range of interventions aimed at the family of a person with schizophrenia
Typically offered for a period of 3 to 12 months and includes at least 10 sessions.
These interventions aim to reduce the level of expressed emotion within the family.
Involves providing family members with information about schizophrenia and finding ways of supporting the schizophrenic individual.
- By reducing levels of expressed emotion and stress, family therapy aims to reduce relapse rates for individuals with schizophrenia.
Pharoah et al (2010) - Family therapy
Reviewed 53 studies from Europe, Asia and North America which compared the outcomes of family therapy to standard care (medication) alone.
- Mental state: mixed because some studies showed an improvement in the mental state of patients whereas others did not.
- Compliance with medication: family therapy increased patient’s compliance with medication.
- Social functioning: family therapy improved general functioning but didn’t lead to more concrete outcomes e.g. living independently or employment.
- Reduction in relapse and readmission: reduction in relapse and readmission during treatment and 24 months after.
How do token economies work?
Based on the theory of operant conditioning.
Positive reinforcement is very important i.e. an increase in the frequency of a particular behaviour when it is followed by a desirable event.
There are two types of positive reinforcer: primary reinforcers and secondary reinforcers.
To be most effective, a reinforcer must be delivered immediately after a target behaviour is performed. Otherwise, another behaviour (e.g. arguing with another patient) can be reinforced.
To give the neutral tokens value, they need to be repeatedly presented alongside or before the reinforcing stimulus (watching a movie) so eventually the token acquires the same reinforcing properties as the primary reinforcer.
The more rewards or privileges the token can be exchanged for, the more powerful the token becomes. Sran and Borrero (2010) found that participants responded more when tokens could be exchanged for a variety of edible items compared with when the tokens could be exchanged for one edible item.
In the early stages of a token economy, there should be frequent exchange periods so that patients are quickly reinforced and target behaviours will increase in frequency.
Tienari et al (2004) - The diathesis-stress model
Reviewed hospital records for 20,000 Finnish female psychiatric patients.
Looked at those who had been diagnosed with schizophrenic psychoses and who had adopted away one or more of their children. Compared these resulting adopted-away offspring (the high-risk group) with adoptees without this genetic risk (the low-risk group). Both adoptees were independently assessed and the family functioning in adoptive families were assessed.
- Of all adoptees, 14 developed schizophrenia over the study - of these 14, 11 were from the high-risk group and 3 were from the low-risk group. Being reared in a healthy adoptive family had a protective effect even for those with a high genetic risk. Adoptees with a high genetic risk reared in families with ‘healthy’ family functioning were significantly less likely to develop schizophrenia than adoptees with a high genetic risk reared in families with ‘unhealthy’ family functioning.