OCR Psychology A Level Book 2 sample

Brain abnormality explanation of major depression The brain of a person with severe depression appears to differ from the brain of a ‘neurotypical’ person. Most notably the limbic system shows differences in terms of the amount of grey matter and the levels of activity in areas of the brain. The limbic system includes the amygdala and hippocampus. The amygdala Changes in levels of activity in the amygdala are associated with the symptoms of depression. Increases in activity have been found when depressed patients are presented with negative stimuli such as a sad face. In contrast the amygdala of a depressed person shows reduced activity when presented with positive stimuli, such as flowers or a happy face. This suggests that the amygdala regulates emotions, which is disrupted in people with depression. In addition to this, when neuroscientists stimulate the amygdala it can lead to many of the symptoms experienced in depression—this provides strong evidence for the amygdala’s role in depression (Drevets 2017). The hippocampus The hippocampus is significantly smaller in patients with depression—it can be reduced in volume by up to 20% (Sapolsky 2001). The more severe the depression, the more severe the loss of grey matter in the hippocampus. This reduction in grey matter, and therefore function in the hippocampus, may explain why people with depression process emotionally charged memories in dysfunctional ways. Research evidence Yvette Sheline et al . (2001) gave an fMRI scan to a sample of 11 depressed patients and 11 control participants. The scan showed that the amygdala was more active in those with depression than controls , both during resting states and activity, particularly when they were shown emotional images expressing fear rather than happiness. What’s more, after antidepressant drugs were given to depressed patients there was a reduction in activity in the amygdala, demonstrating the role that activity in the amygdala plays in depression. Analysing MRI scans , Klaus-Thomas Kronmüller et al. (2008) reported significantly smaller hippocampi in 33 female and 24 male patients who relapsed after two years of being treated for depression compared with a control group of 30 healthy individuals. This was particularly the case for male patients. This implies that the volume of the hippocampus is associated with the likelihood of a person experiencing severe depression. Background The medical model Topic 2 The specification requires that you know the background to the medical model of mental illness. For topic 2 this is divided into three parts: the biochemical explanation, the genetic explanation and the brain abnormality explanation of mental illness. On this spread we look at the third part, the brain abnormality explanation of mental illness. This spread covers the essential information you will need on background for the exam but you also need to link the background to issues and debates and to the key research. We will look at these links on page 30. Brain abnormality principles Localisation of brain functions Localisation means that particular areas of the brain do particular jobs. You looked at localised functions of areas of the brain in the biological core studies, such as Maguire et al. ’s study of taxi drivers. If certain areas of the brain develop abnormally or become damaged through illness or injury, then the functions that those areas control may be affected. Some key areas for mental illness include: • The prefrontal cortex is associated with behavioural control. Individuals with damage to this region have less self-control and have impaired emotional processing. • The limbic system is largely responsible for processing emotions and stress responses and is made up of various structures including the amygdala and the hippocampus . • The amygdala is responsible for feelings of fear and also stores emotional memories. • The hippocampus is responsible for processing memories, and responding to stress hormones. When damaged, the hippocampus is associated with memory loss, particularly for emotionally charged events. The limbic system plays an important role in emotion. It contains several structures including the amygdala and hippocampus, which are both involved in depression and anxiety disorders (e.g. phobias). The brain abnormality explanation of mental illness Brain abnormality as an explanation of mental illness refers to how a mentally ill patient’s brain is different from a neurotypical person’s brain, or how an individual’s brain differs from when they were healthy to when they were mentally ill. Until relatively recently, studies could not be conducted using the brains of living people, therefore research relied on post-mortems . However, since the development of scanning techniques research can be carried out into the structure and function of the brains of individuals with or without mental illness whilst they are alive. Brain abnormality as an explanation of mental illness Prefrontal cortex Amygdala Hippocampus Chapter 1: Issues in mental health 26