The intricacies of our bodies, especially our brains, are presumed to be involved in the origins and maintenance of anxiety disorders. As mentioned, biological factors or vulnerabilities usually have to be in place for an anxiety disorder to manifest.
Schizophrenia Describe and evaluate biological explanations of schizophrenia 24 marks Schizophrenia is a psychotic disorder characterized by distorted thinking, impaired emotional responses, poor interpersonal skills and a distortion of reality. It is the most common of psychotic disorders that, in most countries around the world, affects around 1 per cent of the population.
Whereas psychological explanations tend to focus on cognitive, emotional and environmental factors that may cause the disorder, biological explanations tend to focus on genetic, biochemical and neuro-anatomical factors as the cause of the disorder.
Schizophrenia appears to run in families, and Gottesman has shown through a series of controlled genetic correlational studies that the likelihood of an individual developing schizophrenia is proportional to the amount of genes they share with somebody affected by schizophrenia.
For example, children with two schizophrenic parents have a concordance rate of Biological factors involved in stress essay per cent, monozygotic MZ twins have a concordance rate of 48 per cent, and dizygotic DZ twins have a concordance rate of 17 per cent.
However, from these studies it has also been made clear that genetic factors cannot be the only explanation for schizophrenia.
Although genetic studies support the argument for a genetic basis for the disorder, they have also shown that even when the relative is genetically identical — like monozygotic twins — the chance of developing schizophrenia is below 50 per cent. This implies therefore, that heredity factors are not the primary cause of schizophrenia, other factors are clearly involved.
In addition to this, many researchers have suggested that the reason that schizophrenia appears to run in families could be due to common rearing patterns and that genetic factors are comparatively uninvolved.
In an attempt to disentangle controversy surrounding genetic and environmental factors, twin studies and adoption studies have been carried out.
With twin studies the underlying assumption has been that monozygotic twins will show a greater concordance rate than dizygotic twins as they are genetically identical, and many studies have supported this assumption.
Although many twin studies do consistently reveal a greater concordance rate in monozygotic twins than dizygotic twins, the extent to which this is the case varies greatly. For example, Cardno et al showed a concordance rate of There are several issues with this kind of research, however.
As only 1 per cent of the population is schizophrenic and around 0. This means that sample sizes in these studies are usually very small and so researchers have difficulty generalizing results to the entire population. In addition, twin studies do not all use the same diagnostic criteria and so comparisons cannot always be made McGuffin et al,and concordance rates can be calculated in different ways and vary depending on the method used — meaning that twin studies can lack reliability.
Also a crucial assumption underlying twin studies is that, in general, the environments for monozygotic and dizygotic twins are equivalent and therefore the greater concordance rate in monozygotic twins is due to genetic factors. As Joseph pointed out, however, this is not always the case.
Therefore Joseph argues that the greater concordance rate seen in monozygotic twins than in dizygotic twins is a result of the differing attitudes and environments experienced by the two types of twins. Adoption studies have also been used to determine whether home environment or genetic disposition are more influential in the causation of schizophrenia, as usually in twin studies twins are both genetically related and experience the same environment.
Kety found high rates of schizophrenia in individuals whose biological parents were schizophrenic but were adopted by psychologically healthy parents. The most methodologically sound of adoption studies, though, was carried out by Tienari et al in Finland.
In the study adoptees whose biological mothers were schizophrenic were compared to adoptees whose mothers were psychologically healthy.
It was found that 6. Despite this, there are still potential problems with adoption studies. This could lead to differences in the type of adoptive parents and thus could account for some of the differences seen in the development of schizophrenia between adoptees whose biological mother was schizophrenic and adoptees whose biological mother was psychologically healthy.
The dopamine hypothesis states that the positive symptoms of schizophrenia are produced by overactivity of synapses that use dopamine as a transmitter substance. A variety of drugs used in the treatment of schizophrenia could support the dopamine hypothesis.
Phenothiazines, for example, that work by blocking dopamine at the synapse, have been effective in alleviating major symptoms of schizophrenia. The drug works by increasing dopamine levels, but this has also been known to simultaneously provoke the development of schizophrenic-type symptoms Grilly, Amphetamines, used as stimulant drugs that act by increasing the availability of dopamine and noradrenaline in the brain, can also induce severe symptoms of paranoid schizophrenia in those who were previously unaffected by the disorder.
Evidence from PET scans can also support the dopamine hypothesis. For example, Wong et al found a two-fold increase in the density of dopamine receptor sites in schizophrenic patients that had never been treated with drugs compared to schizophrenic patients who had been treated with drugs.
Issues with the dopamine hypothesis are in abundance in spite of supporting evidence. Drugs used to treat schizophrenia, like phenothiazines, do not work for everybody and, even when they do, only alleviate the positive symptoms of schizophrenia.
Also, post-mortem examinations used as evidence to support the dopamine hypothesis are usually carried out on patients that have been taking neuroleptic drugs for years, meaning that it is difficult to tell whether alterations in dopamine receptor sites were caused by schizophrenia or the drugs themselves.
It has, in fact, been found that the drugs used to treat schizophrenia by blocking dopamine activity can, paradoxically, increase it as neurons struggle to compensate for the sudden deficiency. Haraczin a review of post-mortem studies of schizophrenics, found that many of those who displayed elevated dopamine levels were receiving antipsychotic drugs shortly before death.The human body is an amazing and very complex organism.
The intricacies of our bodies, especially our brains, are presumed to be involved in the origins and maintenance of anxiety disorders. As mentioned, biological factors (or vulnerabilities) usually have to be in place for an anxiety disorder to.
The process of physiological stress response starts from the moment the body realizes the presence of the stressor, followed by the sending of signals to the brain, and to the specific sympathetic and hormonal responses to eliminate, reduce or cope with the stress.
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Essay on Biological Factors involved in Stress Words 7 Pages Psychological and physical well-being and the overall quality of life are under a constant threat of stress and thus, psychological and medical sciences have long been concerned with studying stress response.
Essay on Biological Factors involved in Stress Words | 7 Pages. are under a constant threat of stress and thus, psychological and medical sciences have long been concerned with studying stress . The evidence for biological factors in the onset and progress of depression is strong but not as strong as that for schizophrenia; as with schizophrenia, many of these biological factors (i.e.
genes, biochemical factors) are not ultimate causes and may be only peripherally or indirectly involved.