Why do we need a diagnosis? Maybe a syndrome is enough?

Abstract

The recent publication of the Diagnostic and Statistical Manual of Mental Disorders 5.1 by the American Psychiatric Association, and the continuing work of the World Health Organization on the 11th revision of the International Classification of Diseases raises once more the question of the need for, the use, and the usefulness of diagnosis in psychiatry The fact that, despite significant advances of science, we are still uncertain about the causes and pathogenesis of mental disorders seems to support the notion that it would be better to use syndromes instead of diagnoses, or go even further and describe mental states in health and disease by a series of ratings on key dimensions of mental functioning. Another option that has also received some backing is the presentation of the universe of mental illness by a series of disease prototypes which, it is argued, would be particularly attractive to practising clinicians. The paper discusses these issues and ends by supporting the use of different ways of presenting mental illness, depending on the purpose of the description.

The two questions in the title of this editorial were formulated for me by the editors of this journal. For an issue of Dialogue in Clinical Neurosciences devoted to nosology, they could have added other questions: Why do we need a classification that will group diagnoses into categories? Why do we not report on our work in terms of symptoms which are sometimes the main target for investigation and treatment? Why do we not use categories describing the level of impairment or the degree of disability when talking about patients? and so on.

The abundance of questions of this type is the sad consequence of the fact that science and experience have so far failed to define a single disease in the field of psychiatry. The term “disease” can be used for conditions for which we have: (i) discovered the causes; (ii) understood the pathogenesis, (iii) comprehensively described the clinical picture and the reaction to treatment; and (iv) measured the natural history. None of the illnesses with which psychiatrists deal satisfies these criteria. In fact, it is probable that a condition for which we have fulfilled the five criteria would migrate to another chapter of the classification of diseases, and that its treatment would be entrusted to practitioners of a medical discipline other than psychiatry.

The English language has at least three terms that describe states that might require the attention of a psychiatrist. The term disease refers to a medical condition satisfying the criteria listed above; the term illness refers to the experience of the person who consults a psychiatrist; and the term sickness is used to describe conditions that the society considers “legitimate,” ie, impairing individuals to a level where they can expect to receive benefits (“sickness benefits”) from society. The areas covered by the three terms are only partially overlapping: there are people who have a disease but do not feel ill, others who feel ill but have no disease, and yet others who are subjects of abuse of psychiatry, and are being treated against their will because of a sickness which is not a disease in the sense described above, but has been declared as a sickness requiring treatment by society.

Since the term “diagnosis” should be employed to describe diseases, it might be sufficient that psychiatry in practice uses only syndromes to describe the state of the patient, to define treatment, and to report on the success of their interventions. It is, however, also reasonable to use diagnoses, providing that for the time being we see them as hypotheses about the origins of the conditions, about their pathogenesis, and about their reaction to treatment. In this way the answer to the editors' question is that we should use both in describing the patient's condition—the syndrome which will direct us to the treatment or other intervention, and the diagnosis as an indication of the direction in which we should search for the causes of the condition and for an understanding of its pathogenesis.

We might in fact be much better placed in our exploration of the nature of mental disorders if we were to systematically record not only the syndrome and the diagnosis, but also other characteristics of those who have a mental disorder, doing so along the natural history timeline of the patients' condition. While shorthand—such as a syndrome that can convey some information to others dealing with the care of the patient—is helpful in clinical practice it contributes little to our understanding of the disorder or of the patients' condition if it is the only or the main statement about the patients“ ailment. The comprehensive descriptions of the patients' conditions and of their development are invaluable not only in the generation of hypotheses and in choosing directions of research, but also in deciding on the best treatment and rehabilitation strategies.

The fact that psychiatrists have less and less time should not affect the collection of data necessary for the comprehensive description of the patients' condition. The result of the exploration of the clinical condition in the context of a patient's life cannot, for the time being, be replaced by laboratory findings nor by neuroimaging and electroencephalographic recordings. The summary of the observations of a skillful clinician—including a diagnosis and a mention of the syndrome that has been observed—remains one of the main tools of work in psychiatry, and its preparation should be given priority because it can be the best guide for the treatment of mental illness, for decisions about directions of research, and for the organization of education of all categories of health personnel. The answer to the editors' question is therefore not diagnosis, nor syndrome, but both, as well as other information about the patient's life and illness relevant to the understanding of the mental disorder and of the individual who suffers from it.