- Created by: henrietta
- Created on: 10-06-14 16:43
Classification and diagnosis of schizophrenia
Schizophrenia is a serious mental disorder characterised by severe mental psychological function and loss of reality control. Schizophrenia is split into both positive and negative symptoms when trying to classify and diagnose someone. The DSM was designed to classify psychiatric disorders, which is thought to improve reliability of classification, this is because it is used universally so every patient would be diagnosed using the same system. The reliability can be measured in terms of inter-rater reliability, cognitive tests such as RBANS are important in diagnosis because they measure the degree of neuropsychological impairment. The reliability of tests such as RBANS can be measured in terms of test-retest; repeating the test to see if it produces consistent results. Positive symptoms are those that cause an excess of normal functions i.e. auditory hallucinations, thought control, delusions and incoherent speech. Negative symptoms are those that reflect a loss of normal functions i.e. social withdrawal, apathy, lack of motivation and flatness of emotions. Schizophrenia can be divided into 5 different subtypes, these are paranoid, disorganised, catatonic, undifferentiated and residual.
Biological explanations of schizophrenia
Biological explanations of schizophrenia claim that it’s due to faulty biological functions in the body. The first explanation is genetics; Gottesman and Fields looked at medical records of 57 schizophrenics, 23 were monozygotic and 34 were dizygotic. If a monozygotic twin had schizophrenia, the chance that their twin also did was 48%. If one dizygotic twin had schizophrenia, the chance that their twin had it was 17%, the concordance rate for siblings was 9%. The fact that the concordance rate for monozygotic twins was higher than dizygotic implies that schizophrenia has some kind of genetic basis. However, dizygotic twins and normal siblings share the same amount of genes but have different concordance rates, similarly monozygotic twins do not have a concordance rate of 100%, and therefore an environmental factor is implied.
The next explanation is the dopamine hypothesis which states that schizophrenia is results from an excess of dopamine activity. This is due to either a release of excess dopamine, or excess/over-sensitivity of dopamine receptors. Schizophrenics are thought to have an abnormal amount of D2 receptors, resulting in more dopamine. Amphetamines are dopamine agonists that cause the synapse to be flooded with dopamine, this has been found to cause hallucinations and delusions (schizophrenic symptoms) thus supporting that idea that dopamine is linked to schizophrenia. Similarly, L-dopa is a drug used by people with Parkinson’s disease and increases dopamine levels. This has also been shown to produce schizophrenic symptoms in previously unaffected patients. Finally, antipsychotics work by blocking dopamine activity, these have been shown to eliminate symptoms in schizophrenic patients.
The final biological explanation is abnormalities in brain structure. Research has shown that the frontal lobes of the brain are much smaller and symmetrical as opposed to asymmetrical in schizophrenic patients, meaning there is reduced blood flow. Similarly, CT scans have shown that schizophrenic patients also have enlarged ventricles, however this has only been shown…