Bakground

• The medical model of psychopathology views psychological disorders as being the result of biological malfunctions or disruption. For example, the brain chemistry or neural activity in certain regions of the brain. The underlying causes are also viewed as biological in origin, for example faulty genes or brain damage.
• The monoamine hypothesis of depression - a group of monoamines appear to be involved in depression. These include serotonin, noradrenaline and dopamine. Reductions in serotonin levels, which typically follow stressful events, lead to a failure to regulate normal dopamine and noradrenalin function which in turn disrupts mood and activity levels.
• The dopamine hypothesis of schizophrenia - an excess in dopamine in areas of the brain responsible for speech production may cause hallucinations of voices. Furthermore, reduced dopamine levels in the pre-frontal cortex which is responsible for thinking and decision making may explain other symptoms of schizophrenia such as incoherent thoughts.
• Genetic explanations for mental illness - there is some evidence that certain disorders are passed from one parent to a child through genetic transference. Monozygotic twins (One egg) are the closest you can get to shared genes. Concordance rates of Sz in identical twins are 58% and 12% in non-identical twins. This suggests there is a genetic basis but as there isn’t 100% concordance rates for Sz in twins this explanations would suggestion the environment (nurture) also plays a significant role.
• Brain abnormality - certain brain structures may develop with a different size or shape, and levels of activity can be higher or lower in particular brain regions. Particular areas of the brain also appear to malfunction during mental disorder.
• Brain abnormality and depression - there is some evidence (Coffey 1993) that the frontal lobes responsible for thinking in depressed patients are significantly smaller in volume compared to non-depressed patients identified using an MRI scanner.
• Brain abnormality Schizophrenia - there is evidence to suggest that in Sz the left hemisphere of the brain does not function properly. This was measured by Purdon (2001) who compared the force applied with the left and right hand in 21 patients with Sz and in a control group, the force applied in the right hand of the Sz patients was weaker than controls. 10 of the treatment group were given antipsychotic medication and tested again where the force applied increased.