Example of Academic Writing

Issues surrounding the classification and diagnosis of depression 

The biological model makes the assumption that mental illness can be classified and this means that by identifying symptoms, it should be possible to tell wether or not a person has depression. There are 2 main systems of classification- DSM and ICD. 

One important issue surrounding the classification and diagnosis of depression is reliability which is a measure of the consistency of the diagnosis obtained when the criteria are applied to a person who is depressed. It is desirable that multiple psychiatrists would achieve the same diagnosis when presented with the same set of symptoms. Inter-rater reliability occurs when several practitioners make identical, independent diagnosis of the same patient and though high inter-rater reliability does not guarantee internal validity, low inter-rater reliability is an indicator of poor internal validity. A major problem is that moods vary over time is most people and therefore the reliable diagnosing of depression is difficult. There is a research support for this as Baca-Garcia et al found a concordance rate of only 55% when reviewed the reliability of diagnosis of over 2,300 patients, assessing at least ten times each. This means that reliability of diagnosis over time is relatively poor. However, Keller et al recruited 524 depressed individuals from different clinical sited and it was found that when each one was interviewed using the DSM criteria and interviewed again 6 moths later to establish reliability, inter-rater reliability was indeed high. Generally speaking, studies of DSM show very good inter-rater reliability. For example, Zanariny found an inter-rater reliability of +0.8 for diagnosis of MDD. However, the same researcher found a test- retest correlation of +0.1 within 1 week period. Such reliability studies are also influenced by a quality of information given to the doctor. Zimmerman developed a shorter version of DSM and it increased inter-rater reliability to 95%

Another serious issue is internal validity. There is an assumption that depression can be distinguished clearly from other mental disorders and the accurate diagnosis of depression can based on a set of symptoms. The problem is that, for example, DSM adopts a binary approach of the diagnosis of depression. It suggests that an individual either has depression or does not. Therefore, DSM fails to distinguish between levels of depression and this may have serious implications for treatments as it is possible that some people receive treatment they do not need. Part of the reason is that the symptoms ofter are quite similar to those of other conditions (e.g. sleep disruption is ofter a symptom of both anxiety disorders and depression). For example, Descriptive validity is reduced by comorbidity, where patients have to or more disorders simultaneously, suggesting that such disorders are not actually separate. There is a lot of research support demonstrating that depression occurs comordibly with other illness. Kessler et al found that 74% of people with MDD suffer from another disorder at the same time making patine possible to be given an inappropriate treatment. 

A problem with DSM is the fact that, unlike ICD, it fails to distinguish between levels of severity of depression. This can have a serious consequences since research by Elken et al suggests that only severely depressed people should be given drug treatment. DSM diagnosis can be supplemented by the use of diagnosis inventories such as BDI, which gives each patient a score that measures their level of depression. This helps to to asses patient’s improvements sue to the treatment given as well. However, a problem with inventories is a self-presentation bias which can lead a patient to not answer truthfully. 

The fact that there are two classification systems lead to a major issue within the area of classification and diagnosis. International collaboration is essential as the reliability and validity of classification systems reflects western cultures and therefore can not necessarily assess people of other cultures. As well as that, the doctor doing the diagnosis is not always objective and may bring the gender, race and social class biases into the session. For example, Weel-Baumgarten in 2006 concluded that GP diagnosis of depression was sometimes biased because the GPs were aware of the existence of a family history of the depression. Stirling et al found that if GPs were given extra time in which to make a diagnosis, there was a 32% increase in accuracy. This means that a work pressure faced by the doctor may be a reason for inaccuracy to be created rather than problems within the classification system