"Patients cannot be treated if they are not diagnosed". Is this true?

Although it at first appears self-evident that if patients are not accurately diagnosed with a particular mental disorder, then they cannot be treated with the best known therapy, the process of classification and diagnosis has been plagued by criticism. It seems clear that it is only possible to gain an understanding of the psychological systems underlying a mental illness, if it is properly identified and can be distinguished from other mental disorders. It is this very aim of classification, however, which has been the most attacked, mainly by those who prefer to view "abnormality" as the extreme end of a continuum on which we all lie. If this is true, then the categorical classification systems used by most of psychiatry and psychology may be imposing cut-off points on an entity which would be more accurately reflected in a continuous manner. Nonetheless, some method of diagnosis is clearly essential, since research shows that different syndromes respond differently to different treatments. If a schizophrenic patient were to be misdiagnosed as depressed and then treated as such, the results could be disastrous. Clearly then, although current methods of diagnosis need to be much improved, at the moment they are better than no diagnosis at all, at least from the patients' point of view.

The process of classification used in psychiatry stems from the medical model of diseases. This assumes that there exist a finite number of disease entities, each with a distinct cause, psychological pattern, outcome and cerebral pathology. The main problem with using this model as a basis for classifying mental disorders, is that it implies that abnormality is a clear departure from a well-defined pattern of normality. This begs the question of what exactly "abnormality" is. It has been suggested (Rosenhan and Seligman (1989), in Eysenck (1994), that abnormal behaviour involves seven different features - suffering, maladaptiveness, vividness and unconventionality, unpredictability and loss of control, irrationality and incomprehensibility, observer discomfort and violation of moral and ideal standards. Even ignoring the fact that many of these abnormal features are possessed by people we would call merely eccentric or idiosyncratic, where does one draw the line between normal and abnormal? How many features are required for an individual to be classified as mentally disturbed? This is clearly highly subjective, and therein lies much of the difficulty with a medical model of classification - not only do psychiatrists have to make a highly personal, and often arbitrary, judgement about what is normal behaviour, they also usually only have the patient's description of how he feels to go on.

The problem of diagnosis has been amusingly summed up by Bentall (1992) in his proposal to classify happiness as a psychiatric disorder. He suggests that since happiness is statistically abnormal, is made up of a discrete cluster of symptoms and is associated with a range of cognitive abnormalities, such as an impaired recollection of unhappy memories, it clearly conforms to the criteria of a mental disease and should be classified as such. Although Bentall's critique of the method of classification used in psychiatry makes some valid points about how we decide what is normal and what is abnormal behaviour, his implication that because it would be absurd to classify happiness as a disease on the basis of these criteria, it is also absurd to classify schizophrenia in this way, does not follow (Harris, Birley and Fulford, 1993). Although the problem of how this disorder is diagnosed is a real one, its symptoms exist whether or not we classify them, and to suggest they do not is very unhelpful.

The categorical classification of mental disorders is clearly problematic, since it postulates discrete diagnostic entities and does not allow the continuum between normal and abnormal behaviour which many believe exists. Furthermore, the more severe the general clinical state, the greater the appearance of discontinuity in behaviour, even if this is not an accurate reflection of reality (Claridge, 1995). It has been suggested, therefore, that a dimensional classification, ranked on a quantitative scale, should be used instead. Eysenck (1952, in Cooper and Cooper, 1988) is particularly for this type of continuous classification, arguing that normal and abnormal differ only in intensity and not in kind. Evidence for this comes from the finding that psychoticism and neuroticism are dimensional variables, with a continuity between the normal and abnormal populations. Furthermore, attempts to establish genuine points of rarity between disorders produced little evidence that interforms between adjacent disorders are less common than the two disorders themselves. An advantage of continuous classification is that it can subsume a categorical system by specifying a threshold on one of the quantitative dimensions if needed, since it is sometimes useful to create a category for people with extreme symptoms.

The general process of classification has also been criticised, since to classify someone necessarily results in the loss of information about that person's uniqueness. What matters, however, is whether the information lost is relevant, and this is especially difficult to judge when dealing with abnormal behaviour. The risk is, therefore, grouping people together on trivial bases and ignoring their extremely important differences. Classification itself can also have negative effects on the person, such as the well-documented stigmatising effects on those labelled schizophrenic. This has led to the Labelling Theory (Scheff, 1966, in Eysenck, 1994), which proposes that the label itself plays a part in creating the symptoms. Nonetheless, classification has some very important aims - it permits the description of disorders, so that psychiatrists can communicate effectively with one another, and it allows theories to be postulated which hopefully lead to treatments and prognoses. In general, it is essential to classify various types of differing abnormal behaviour because these differences may be the key to their treatment or prevention.

The most recent classification method is the Diagnostic and Statistical Manual of mental Disorders (DSM-4), which is made up of multiaxial classes, resulting in each individual being rated on five dimensions. These are - all categories of mental disorder, personality disorders and mental retardation, general medical conditions which may affect the mental disorder in question, psychosocial and environmental problems and the current level of adaptive functioning, rated 100 to 1. This classificatory method anticipates that common aetiologies will lead to diagnoses-specific treatment, and has made uniform diagnostic practices possible, even in the absence of shared aetiological theories. It has been suggested (Robins and Helzer, 1986), that the current scheme is only a set of hypotheses about reality, which are subject to change and development based on empirical research, and the value of such a scheme is that it can be tested for reliability and validity. Reliability refers to the extent to which the classification system produces the same diagnoses each time it is applied to the same person and interrater reliability is the extent to which two judges agree with each other. Reliabilities for DSM-4 are relatively high, especially for bipolar disorder (.84), major depression (.64) and schizophrenia (.65). As far as validity is concerned, there are many different types, such as aetiological validity (the extent to which the same causal factors are found in the people in a diagnostic group) and concurrent validity (when other symptoms not part of the diagnosis itself are found to be characteristic of those diagnosed). The most important form of validity for classification systems, however, is construct validity, which means the extent to which accurate statements and predictions about the future can be made from the diagnosis. It has been argued that the predictive validity of DSM-4 is quite low (Eysenck, 1994), since for disorders such as schizophrenia there is no single form of treatment which is effective, but for other disorders such predictive validity is relatively high. 70% of patients with unipolar depression respond well to tricyclic anti-depressants, for example, and 80% of patients with bipolar depression respond well to lithium.

It seems, then, that at best diagnoses are imperfect descriptions of reality, and that they do not fully assess the uniqueness of the individual and tend to use arbitrary cut-off points that exclude some people who require treatment and include others who do not. Nonetheless, diagnoses from a well-structured system provide a highly useful way of understanding patients' history and predicting their future. As long as methods of classification are constantly being researched and improved, diagnoses remain the best way of finding out how to effectively treat patients.

References

Bentall (1992). A proposal to classify happiness as a psychiatric disorder. Journal of Medical Ethics, 18, 94-98

Claridge (1995). Origins of Mental Illness.

Cooper and Cooper (1988). Classification and Diagnosis. In Miller and Cooper (Eds.). Adult Abnormal Psychology. Churchill Livingstone. Edinburgh

Davison and Neale (1998). Abnormal Psychology. Wiley

Eysenck (1994). Individual Differences: Normal and Abnormal. Lawrence Erlbaum Associates

Harris, Birley and Fulford (1993). A proposal to classify happiness as a psychiatric disorder. British Journal of Psychiatry, 162, 539-542

Robins and Helzer (1986). Diagnosis and clinical assessment: The current state of psychiatric diagnosis. Annual Review of Psychology, 37, 409-432

Obviously well researched and skilfully presented. There is very little I can say that would improve it. The only thing that I might want to include is perhaps a brief assessment of the impact of genetics on classification. This applies generally to the issues of classification and the aetiology of disease, it especially supports the idea of a continuum. The new models of disease based on genetic information also relates eminently to the traditional diathesis-stress model, since genetics so clearly is based on probabilities and gene-environment interaction.

Specific good points: (1) sound selection of arguments; (2) continuous referral back to the literature; (3) going back to the essay question/topic in the conclusion.