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42195751133475Biochemical explanations For us to think, feel or make decisions, our brain cells must transmit information in the form of electrical impulses around the brain. Each brain cell transmits information to the next through a synapse. Chemicals called neurotransmitters must pass through synapse for information to pass. One explanation for mental illness involves the possibility that symptoms are as a result of abnormal neurotransmitter levels.Biochemical explanations for…DepressionA group of neurotransmitters called the monoamines appear to be involved in depression. These monoamines include; serotonin, noradrenaline and dopamine. Research suggests dopamine is responsible for mood. Serotonin is thought to control the activity of dopamine and noradrenaline. And so, if serotonin levels are low this means the dopamine is not regulated and can have a negative effect on mood.One version of monoamine hypothesis of depression says that reductions in serotonin levels which typically follow stressful events leads to failure to regulate dopamine and noradrenaline function normally. This leads to disrupted moods and activity levelsSchizophreniaHigh levels of dopamine in certain areas of the brain responsible for speech production may cause symptoms of schizophrenia eg hallucinations of voices. More recently, a new take on the dopamine hypothesis has focused instead on reduced dopamine levels or activity in the brains cortex (Goldman-Rakic et al. 2004). Thus, low levels or activity of dopamine in the prefrontal cortex which is responsible for thinking and decision-making may explain other symptoms of schizophrenia, including apathy and incoherent thought or speech.HOWEVER… Did the imbalance cause the mental health issue or did the mental health issue cause the imbalance?36766508572500Brain abnormality It is thought that the structure of one’s brain and its function is linked to mental illness. For example, certain structures in the brain may develop with a different size or shape and levels of electrical activity can be higher or lower in particular areas of the brainBrain abnormality as an explanation for…DepressionEvidence exists which suggest depression occurs as a result of brain abnormality. Some studies suggest the importance of the frontal lobe – the region of the brain, which is involved with thinking.Coffey (1993) compared the size of depressed patients and non-depressed patients using an MRI scanner. He found the mean frontal lobe volume in depressed patients was significantly smallerSchizophreniaThere is also evidence, which suggest that schizophrenia occurs due to the left hemisphere of the brain not functioning normally.Purdon (2001) compared the force of the right and left hand in 21 patients with schizophrenia and a control group. Ten in the treatment group were given antipsychotic medication and tested again. Compared to the treated group, the untreated group were significantly weaker in right hand, not left. Why would a weakness in the right hand mean their left hemisphere isn’t functioning correctly??There is also evidence to suggest that negative symptoms of schizophrenia, such as loss of motivation, are associated with brain abnormalities. Motivation (in particular the anticipation of a reward) is believed to involve a brain region called ventral striatum in schizophrenia. Jucket 2006 found lower levels of activity in VS amongst schizophrenics than controls. Jucket found negative correlation between these variables (lower the activity levels fall, the higher the occurrence of negative symptoms).Hallucinations are also associated with abnormal brain function. Allen et al. 2007 scanned brains of those experiencing auditory hallucinations. He compared these to a control group. Lower activation levels found in two brain regions – superior temporal gyrus and anterior cingulate gyrus – were found in hallucination group (than control). It can be concluded abnormal function in these areas is associated with hallucinations in schizophrenia Genetic explanation3400425952500As humans, we randomly inherit half of our genetic material from mother and other half from father. Our total genetic makeup of individual is known as genotype. It is unlikely any mental illness is purely result of genetic factors; however, it does appear that some people are more vulnerable than others to developing mental health issues as a result of genetic makeup.Genetic explanation for…DepressionThe strongest predictor of depression is the experience of stressful life events. However, we do not all respond to the same stressor in the same way. More recent research looks at the influence of particular genes and how those genes interact with the environment, together influencing symptoms.Researchers are interested in looking at the serotonin transporter gene. This is responsible for producing serotonin in the brain. The gene comes in three forms, varying in length of strands; Long-long, long-short, short-short. Short short is believed to lead to inefficient serotonin production. This means those with SS are less resilient than others to stress and more vulnerable to depression.SchizophreniaSchizophrenia runs in families. However this does not necessarily mean it is genetic in origin, Families share genetics and environment! There is a strong relationship between genetic similarity and risk of developing schizophrenia (see figure 1.13, on page 27). Exam question:Outline one biological explanation of mental disorders (5 marks)Structure:State and explain biological explanation (3 marks)Link biological explanation to a specific disorder (2 marks) ................
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