Tauscher et al (2014) found that giving patients antipsychotic drugs which lower dopamine levels (antagonists- reducing activity) reduced the occurrence of positive symptoms, supporting the hyperdopaminergia aspect of the hypothesis.Curran et al (2004) found that dopamine agonists (drugs which increase activity) produce schizophrenia-type symptoms in patients, supporting the hypodopaminergia aspect of the dopamine hypothesis.This is linked with negative symptoms, as there is a reducing in normal functioning. Hypodopamineriga: This refers to lower than usual levels of dopamine in the cortex (outer part of the brain), where less dopamine is being transmitted across synapses. There may be a higher number of dopamine receptors, causing over-activity of dopamine, causing sensory hallucinations. This is linked with positive symptoms such as hallucinations. Hyperdopaminergia: This refers to higher than usual levels of dopamine in the subcortex (central areas of the brain). As it is only around 50%, this suggests other influences are playing a part.ĭopamine is a neurotransmitter, the levels of which seem to be associated with schizophrenia symptoms. As identical twins share 100% of their genes, it would be expected that the concordance rate for schizophrenia would be 100% if it was purely genetic.This means that it can’t be concluded that genetics has caused schizophrenia. For example, identical twins share the same environment (and may be treated similarly), whereas first cousins would not. It may be that the increased concordance rates in the Gottesman study were due to the increased chance of sharing the same environment as the person with schizophrenia.Tienari et al (2004) found that adopted children of biological mothers with schizophrenia were more likely to develop the disorder themselves than adopted children of mothers without schizophrenia, supporting the genetic link.Ripke et al (2014) found 108 genetic variations associated with schizophrenia. It is also aetiologically heterogeneous, meaning different combinations of genes are implicated in the disorder. Schizophrenia is thought to be polygenic, with lots of different genes contributing to an increased risk of developing it. The more genes the person shares with the sufferer, the more likely they are to have the disorder, suggesting there may be a genetic basis for schizophrenia. This means that if a person has the disorder, there is a 48% chance that their identical twin (if they have one) will also have it. Gottesman (1991) found that if a person has schizophrenia, the following concordance rates apply: By studying family members and the occurrence of schizophrenia, this can be investigated. The suggestion here is that schizophrenia runs in families. Dealing with Offending Behaviour: Custodial Sentencing.Psychological Explanations of Offending Behaviour.The Ethological Explanation of Aggression.Research Methods: Scientific Method & Techniques.Explanations of Attachment: Learning Theory.
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