Discuss the genetic and biochemical explanations of schizophrenia
Discuss the genetic and biochemical explanations of schizophrenia (25 marks) Biological explanations have been used in attempting to explain many mental disorders. However, such explanations have proved more successful in accounting for the development of schizophrenia than most other disorders. Two main branches of this type of explanation are genetic factors, which explain schizophrenia through inheritance of abnormal genes; and biochemical factors, which explain schizophrenia through the presence of abnormal neurochemicals. Nonetheless, there is contrasting evidence for both and it has been suggested that you can't completely separate these explanations from each other as schizophrenia is a complex and multi-cause disorder. In order to use twin studies to support genetic explanations of schizophrenia, when one twin is known to be schizophrenic, researchers are interested in the probability that the other twin may also be. This is known as concordance. Gottesman (1991) summarised 40 twin studies and found that the concordance rate was 48% when a monozygotic or identical twin had schizophrenia, but only 17% when a dizygotic twin or non-identical twin had schizophrenia. These findings strongly suggest that genetic factors are important - the reason why identical twins have a much higher concordance rate than fraternal twins is because they are much more similar genetically
Biological Explanations of Schizophrenia
SC1 There is strong evidence that biological factors play a large part in the development of schizophrenia. It has been known for a long time that sch runs in families. This could be because families share the same disadvantaged environments, but research evidence from family, twin and adoption studies suggests that genetic factors are also important. First-degree relatives share an average of 50 per cent of their genes with each other, while second degree relatives share only 25 percent. Research evidence has looked to see if there is a correlational link between inheriting schizophrenia and genetic similarity. Kendler et al (1985) found that first-degree relatives of schizophrenics are 18 times more likely to contract the disorder than the general population. Family studies are often inconclusive because they are conducted retrospectively, after people have been diagnosed. Therefore we can question the reliability of findings, as the relationship between genetic similarity and susceptibility to schizophrenia is not fully clear; a longitudinal study would be better However, a longitudinal study of this nature would be hard and very time consuming to conduct. Twin studies are another way of establishing a genetic link; they look at the difference in concordance between MA and DZ twins. Cardno et al (1999) found a 40 per cent concordance rate of sch in MZ twins, compared
Biological Explanations of Schizophrenia
Discuss research in biological explanations of schizophrenia Schizophrenia is a psychiatric disorder involving loss of contact with reality and a range of symptoms. One biological explanation for schizophrenia is that genetic factors are involved. This view considers that certain individual's posses certain genes which predispose an individual to schizophrenia. Furthermore the condition can be inherited and as a result we would expect to find that relatives have similar chances of developing the disorder. One other biological explanation for schizophrenia is the Viral Hypothesis. This states that schizophrenia is a mental deterioration at an early age. In other words brain damage at the time or before the time of birth could be a factor in the development of schizophrenia. They have enlarged ventricles in their brain and post-mortems have found that their brains are lighter. There certainly evidence that supports that we can inherit a disposition for schizophrenia through genetic causes. Research to prove this comes twin studies of MZ and DZ twins. Gottesman and Shields found a higher concordance rate of MZ twins both having the disorder than DZ twins who only share 50% of their genes, although the concordance rate was not 100%. This certainly highlights the huge influence genetics have on inheriting the condition however, if genetics were the sole cause we would expect
"The biological approach tells us all we need to know about schizophrenia" with reference to the quote discuss genetic explanations of schizophrenia.
"The biological approach tells us all we need to know about schizophrenia" with reference to the quote discuss genetic explanations of schizophrenia. The biological approach claims that schizophrenia is caused by genetic, neurotransmitter or structural brain faults. The first of these is the claim that schizophrenia is genetically passed on; if a relative is diagnosed with schizophrenia the first degree relatives will develop schizophrenia. Grottesman (1991) fount that in monozygotic twins if one was diagnosed with schizophrenia then 48% of the time the other twin would go on to develop schizophrenia. In dizygotic twins Grottesman found that if one was diagnosed with schizophrenia then 18% of the time the other will go on to develop schizophrenia. This shows strong support when compared to the general population where 1% of people are diagnosed with schizophrenia. However, monozygotic twins are often reared in a very similar environment; they were born at about the same time and they get treated similarly. This implies that concordance rates between twins aren't reliable as the children will have been treated similarly therefore environmental factors can be an explanations for the development of schizophrenia in a pair of monozygotic twins. The same can be said for first degree relatives; they will still share a similar environment which could provide an explanation for
Psychological Explanations of Schizophrenia
Discuss research in biological explanations of schizophrenia In order for schizophrenia to be diagnosed the person needs to have two or more of the following symptoms for over 6 months. These are; thought disturbances (positive= bizarre additions to normal behaviour) such as thought insertion, hallucinations and delusions. (negative= absence of normal behaviour) Disturbances of affect/volition such as withdrawal, reduced motivation and difficulty carrying out actions. Thirdly; Psychomotor disturbances such catatatonia, stereotypy and frenetic activity. Research into psychological explanations of schizophrenia had come up with the idea that expressed emotions in families can have considerable affect. This states that families who had high expressed emotion had higher levels of concern or hostility to the sufferer of schizophrenia. This argues that high expressed emotion families can cause schizophrenia. This gives the assumption that schizophrenia can be partly caused by the onset of stress caused by families. This could result from conflicting demands and breakdown in communication with family. This can explain how a child can become confused and doubtful from parents giving conflicting demands. For example a child could be criticised for not giving hugs, when the child tries to give a hug it will be rejected. In this situation the child can not win and can not avoid
Bio explanations of schizophrenia
Biological Explanations of Schizophrenia One biological explanation for schizophrenia is that genetic factors are involved. This view considers that certain individuals possess certain genes which predispose an individual to schizophrenia. This can be explained in more detail using studies on twins. According to research identical twins are said to share 100% of their genes and therefore if one twin has schizophrenia, there's a 48% chance of the other twin developing it too. Gottesman summarised 40 twin studies and found that the concordance rate for MZ twins was 48% and the concordance rate for DZ twins was about 17%. Concordance rates were also studied by Cardano et al using the Maudsley twin register. They found concordance rates to be 40% for MZ twins and 17% for DZ twins. This provides strong evidence in which genetic factors play a key role in schizophrenia. However because concordance rates are not 100%, it is said that there must be some kind of environmental input. Loehlin and Nicholas argued that the reason for higher concordance rates in MZ rather than DZ twins was due to DZ twins being treated more similarly so therefore producing a greater environmental similarity. Nevertheless because schizophrenia has chances of becoming inherited, we would expect to find that relatives also have similar chances of developing this disorder. This is supported by Kendler et al
Discuss biological explanations of schizophrenia
'Research into schizophrenia shows that there is a major genetic component but the fact that concordance rates between identical twins is never 100% means that there must be environmental contributions.' Discuss biological explanations of schizophrenia. (30 marks) Schizophrenia is a psychiatric disorder involving the loss of contact with reality and a range of symptoms. There is considerable evidence that genetic factors are involved. This view considers that certain individuals possess certain genes which predispose them to schizophrenia. This means that it is inherited and we would expect to find that relatives have similar chances of developing the disorder. Indeed research has found that first degree relatives of people with schizophrenia are 18 times more likely to be affected than the general population. Monozygotic twins would be expected to have the same chance of having schizophrenia as they carry the same genes. Research by Gottesman and Shields has found high concordance rates (where both twins have the disorder) in monozygotic twins than in dizygotic. However if schizophrenia was solely caused by genes then we would expect a 100% concordance in monozygotic twins. Since this is not found then other factors must play a part. Mz twin studies have the advantage of controlling for genetics but the disadvantage of not controlling for environment. One way to get
Outline and evaluate two biological explanations of schizophrenia
(a) Outline and evaluate two biological explanations of schizophrenia There are many biological explanations of schizophrenia. In this essay I will concentrate on the genetic explanation and biochemical explanation of the disorder. There are many studies that look in to genetics and the link to schizophrenia. This is dues to an original finding that schizophrenia runs in families and therefore suggests that genes are responsible for the disorder. I study was preformed by Janicak et al 2001; they found that monozygotic twins have a 48% concordance rate. This is considerably less in dizygotic twins where the concordance rate falls to 17%. This would suggest there is a strong case for genetics being involved with schizophrenia. However if the disorder was caused entirely by genetics then we would expect a 100% concordance with monozygotic twins. A supporting study is one by Kety et al. 1988. This study found 14% of biological relatives of schizophrenic adoptee were schizophrenic, and only 2.7% of adoptive relatives. This backs up the claim for genetics although it still suggests there are other factors involved. The stress diathesis model could explain the differences in concordance rates. Gottesman also supports the genetic link, showing schizophrenia is more common in close biological relatives of a schizophrenic. However genetic explanations cannot account for the patients
Marked Essay - Discuss biological explanations of schizophrenia.
‘There is considerable evidence that schizophrenia is caused by biological factors. These can be genetic, neuroanatomical, biochemical, viral or a combination of such factors.’ Discuss biological explanations of schizophrenia. (8 marks + 16 marks) Biological explanations portray behaviour as a product of nature. It has three main assumptions: That human behaviour can be explained by looking at internal, biological structures such as hormones and the nervous system Experimental research that uses animals can be generalised to human behaviour And that abnormal behaviour can be removed using biological treatments- e.g medication for schizophrenia. / Biochemical explanation: Post-mortems and PET scans have shown that schizophrenics have either an abnormally high amount of the neurotransmitter dopamine, a high amount of D2 receptors, very sensitive D2 receptors, or all three. These findings led to the development of the dopamine hypothesis, which states that synapses that use dopamine as a neurotransmitter are overactive in the brains of people with schizophrenia. / A nerve impulse arrives at the synaptic knob of the presynaptic neuron. The arrival stimulates voltage-gated calcium ion channels to open. Calcium ions then diffuse into the synaptic knob. The influx of calcium ions into the synaptic knob causes the synaptic vesicles (containing the neurotransmitter
Outline and evaluate biological explanations for schizophrenia
Outline and evaluate biological explanations for schizophrenia There appears to be a tendency for schizophrenia to run in families. This suggests that genesplay a role. The closer the genetic relationship the more likely the people are to share thedisorder. Evidence from family studies by Gottesman showed that when both parent areschizophrenic then there is a 46% chance of the child getting it, however, if only one parenthad it, it dropped to 16% and dropped to a further 1% when the sibling of the child hadschizophrenia. This suggests that a genetic factor is involved. Gottesman also looked atschizophrenics whose father had an identical twin. He found that there was a 17% of beingschizophrenic when the father was but he also found that there was also 17% chance of developing the disease when the father's twin had schizophrenia but the father didn't.MZ twins share 100% of their genes; DZ twins share 50% of their genes. If genes are a factor we would expect more identical twins to share the disorder than non-identical. Rosenthal tooka case study which had a set of female quadruplets. They all developed schizophreniaalthough the onset and symptoms were very different. This could have been a result of havinga troubled upbringing. This suggests a strong heritable component.However, most first degree relatives and twins share the same or similar environments so it isdifficult to
