Delusion Essay

1315 Words6 Pages
Delusion is a symptom of a number of psychotic disorders such as schizophrenia and mood disorder. German psychiatrist Jasper (1965) defined three criteria for diagnosing delusion: implausibility of believe, imperviousness to counterarguments, and believe in the delusion with certainty. There are several common themes of delusion that are reported. For example, persecutory delusion, where one believes someone has the intention to cause them harm, and delusion of control, where one believes that his/her behaviour is controlled by an external force. Studies have found a number of biological explanations, such as genetics, for the causes of delusional thoughts. This paper will focus on the genetics and neural factors affecting delusion as well as specific types of delusions such as delusion of reference. Lesions in the brain have allowed neurologist to identify the causes of delusion. A study (Devinsky, 2009) has shown that out of 69 patients with reduplicative paramnesia (a delusional believe that a location is incorrectly merged or relocated) who have brain damage, 36 had damaged their right brain compared to 5 who have damaged their left brain. Similar result has been found in people with Capgras delusion (a believe that an acquaintance has been replaced by an imposter) where 8 out of 26 patients have exclusively damaged their right brain compared to 2 for the left brain. Patients with other types of delusion have shown similar result. Furthermore, in the above experiments by Devinsky (2009) have found that almost all the subjects had frontal lobe lesion with the majority being either damage to the bifrontal or right frontal lobe. Frontal lobe damage can cause delusional thoughts such as imperviousness to counterarguments because ... ... middle of paper ... ... been conducted to further enhance our understanding of the various areas of the brain responsible for delusion. Delusion of reference has been linked to over-activity in the cortical midline structures (CMS) and the subcortical regions. The delusion of control on the other hand is caused by the over-activity of the parietal lobe which is in turn is caused by a lack of inhibitory signals from the frontal cortex in response to a voluntary movement. Genetics have also been found to significantly influence the likelihood of a person acquiring delusional symptoms. These studies show that like most other psychological phenomenon, delusion does not have a clear biological basis. Instead, it is influenced by a number of factors such as genetics and environmental causes (e.g. brain damage) and different types of delusion may be influenced by very different neural processes.
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