Discuss biological explanations for depression (24marks) One of the most popular explanations of depression is genetics; this theory states that genes are to blame for the presence of depression. It also argues that depression, like many other illnesses, is an inherited one which runs in families. McGuffin et al (1996) conducted research on concordance rates using 177 identical and fraternal twins. They found that the concordance rate was 46% for identical twins, but only 20% for fraternal twins; these findings are significant as the concordance rate for identical twins is over double of that for fraternal twins. These findings support the biological explanation as it suggests that depression has a genetic factor.
Brain scans can be used to help diagnose some disorders. Furthermore, the genes we are born with, from our parents, provide the blueprint for our bodies and brains. A slight abnormality in our genes can affect the functioning of our brains. Also to operate properly the brain relies on hundreds of chemicals to operate in the correct balance, these chemicals are used to send messages around the brain. Therefore if there are chemical imbalances abnormality may occur, for example low levels of serotonin are linked to depression and schizophrenia is linked with high levels of dopamine.
Outline and evaluate one or more biological explanations for schizophrenia The biochemical explanation is one explanation for the cause of schizophrenia in terms of the release of neurotransmitters. This suggests that schizophrenia could be caused by an excess amount of dopamine in the brain. This is due to receptor cells requiring dopamine to fire so with a large amount of dopamine present it is activated too much and too many messages are sent. This is what could account for the confused and the erratic behaviour which is seen in schizophrenic patients. Support for this theory is the effect of amphetamines.
Antidepressants on the other hand by balancing neurotransmitters such as serotonin and epinephrine witch can cause depression if not sufficiently balanced. Anxiolytic drugs are used to combat anxiety disorders one drug in this field is benzodiazepines (Bzs) they work by releasing more (GABA) witch slows down the nerve transmission calming people down. This drug is effective in areas such as phobias. Another biological therapy is ECT, it is a surgical based treatment commonly used on manic depressives who haven’t responded to antidepressants. This treatment is administrated to a patient by putting a patient into an unconscious state then passing a current of 0.6 amps through the brain.
Gottesman (1991) investigated twin studies of monozygotic and dizygotic twins. He summarized 40 concordance studies and found that when one of the twins was diagnosed with schizophrenia, monozygotic twins showed a 48% concordance rate over a 17% concordance rate in dizygotic twins. Due to the monozygotic twins sharing 100% of their DNA and dizygotic sharing only 50%, this shows that genetics are very likely to play a role in someone developing schizophrenia. However, due to concordance rates not being 100% in MZ twins, it also suggests that some environmental factors must play a role too. Loehlin and Nichols (1976) suggested that the high concordance rates in MZ twins is most likely to be due to the fact they will be treated very
However this study can be criticised because of its retrospective analysis after the disorder had developed, thus it may be more conclusive if a prospective study was conducted to show the ‘before and after’ effects within families. Tienari et al found the risk of developing schizophrenia was 4 times greater in adopted children with biological mothers with schizophrenia than those with ‘healthy’ parents. This again shows a strong genetic link absent of overriding environmental factors. However
The four kinds of medical explanations are: infection, biochemistry, neuroanatomy and genetic factors. From the perspective of infections, microorganisms cause common physical illnesses and have also been attributed to mental disorders, such as schizophrenia. The limitation of this explanation, however, is that although finding a diagnose is the aim of the medical model in order to treat and cure, the majority of mental disorders have multiple
If the caudate nucleus is damaged it fails to suppress the signals from the OFC allowing the thalamus to become hyperactive. Additional inherited possibilities include lower levels of the neurotransmitter serotonin and higher levels of dopamine. Low levels of serotonin have been implicated in OCD as it has been found that antidepressant drugs which increase serotonin levels are affective in reducing symptoms of OCD. Higher levels of dopamine as suspected as a possible cause for OCD because in animals higher levels of dopamine can lead to stereotyped movements that resemble the compulsions found in OCD sufferers. Genetic explanations for OCD are supported by family and twin studies.
The current belief is that there are a number of genes that contribute to susceptibility of schizophrenia, but none exhibit full responsibility for the disease. It is believed that schizophrenia is much like diabetes, which is caused by a number of genetic and environmental factors. Research also increasingly suggests that - like diabetes - many cases of schizophrenia may be
Genetics can help explain addiction, the genetic explanation of addiction focuses on the fact that an individual may have gene which makes them more susceptible to pursue addictive behaviours e.g. drug taking. The A1 variant of the DRD2 gene has been linked with the initiation addiction. People with the A1 variant are said to have few dopamine receptors as a result Noble refers to the gene as the "reward gene", this is because dopamine is a neurotransmitter which we associate with reward and pleasure. Alcohol/drugs can increase the level of dopamine (this compensates for the lack of dopamine receptors in individuals with A1 variant of the DRD2 gene).