Psychology Revision: Schizophrenia
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Clinical characteristics of Schizophrenia:
The diagnostic and statistical manual (DSM) criteria for Schizophrenia is as follows -
For someone to be diagnosed as schizophrenia, they require to have at least 1-month duration of two or more ’positive’ symptoms. ’Positive’ being those that appear to reflect an excess or distortion of normal function.
-Delusions
These are bizarre beliefs that seem real to the schizophrenic yet are not. Sometimes this can be paranonia, for example thinking the behaviour and comments of others (even on tv) are specifically meant for the individual alone, or that they are being watched.
-Experience of control
Individuals may believe they are under control of an alien force that has invaded their minds or body.
-Auditory Hallucinations
These are unreal perceptions of the environment and are usually auditory although sometimes can be visual or tactile.
-Disordered thinking
This refers to the feeling that thoughts have been inserted into or withdrawn from the mind. Sometimes this can be thoughts that others can see what their thinking.
Biological Explanations of Schizophrenia
Genetic factors -
Family studies, such as Gottesman, 1991 have found that schizophrenia is more common in the biological relatives of the schizophrenica, therefore giving strong evidence of genetics being strongly influential on those who have it; Gottesman found that identical twins have a 48% risk of developing schizophrenia, if the other twin has it.
This however also suggests that genetics are not the only factor, because otherwise it would be 100%, therefore most psychologists believe the ‘diathesis-stress’ model to be the best at explaining schizophrenia - Which claims that a biological predisposition for developing schizophrenia exists in genetics, but this may only turn into a disorder if other significant psychological stressors are present as triggers.
Furthermore genetics cannot explain why some patients of the disorder don’t have any close relatives with the disorder, Stirling and Hellewell (1991) found two-thirds of those diagnosed with schizophrenia don’t.
Biochemical Factors -
Dopamine is a neurotransmitter which operates in the brain. Schizophrenics are thought to have an abnormally high number of D2 receptors on their receiving neurons - resulting in more dopamine binding and therefore more neurons firing. Dopamine neurons are key to a persons attention and therefore disturbances in this process may lead to the problems of attention and thoughts found in people with Schizophrenia, (comer,2003). This is known as the dopamine hypothesis.
Evidence comes from antipsychotic drugs. Phenothiazines bind to the D2 receptors, effectively blocking transmissions of nerve impulses through them and therefore reducing the attentional deficit found in schiophrenia.
L-dopa is a drug Parkinson’s diseased patients receive to increase their dopamine and it was found that these patients developed schizophrenic-type symptoms (Grilly, 2002).