Elementary concepts of medicine: V. Disease: one of the main subtypes of illness

To us, the proper general term for ill-health – quite naturally, we believe – is 'illness'; but, as many of the medical dictionary definitions of various concepts related to ill-health already quoted in the preceding essays indicate, the term for ill-health at large in most common usage at present is 'disease'. Indeed, in neither one of our medical dictionaries (Dorland 1994; Stedman 1995) does the definition of disease in any way indicate that at issue is a subtype of ill-health. More than that, disease is explicitly said to be 'any[italics added] deviation from . . . the normal structure or function . . . of the body . . .' (Dorland 1994), or something very close to this (Stedman 1995). 'Morbus' is identified as a synonym for 'disease' (Dorland 1994; Stedman 1995). If we were to accept the idea that all forms of ill-health are diseases, then we would have to think of somatic defect and injury as diseases (or, as the only alternative possibility, as conditions of 'normal structure or function'). We have, however, serious difficulties with the implications of that comprehensive conception of disease. Defect in one of the dictionaries (Dorland 1994) is defined as 'an imperfection, failure, or absence', the definition supplemented with examples such as 'congenital d.', 'neural tube d.' and 'ventricular septal d.'. The other dictionary (Stedman 1995) defines defect as 'an imperfection, malformation, dysfunction, or absence; an attribute of quality, in contrast with deficiency, which is an attribute of quantity'. In the latter source, examples similar to those in the former one are given. While at issue obviously is a 'deviation from the normal structure or function', neither dictionary identifies defect to be a disease (as the proximate genus). 'Vitium' is said to be 'fault, defect' (Dorland 1994) or is left undefined (Stedman 1995). For injury, one of the definitions is: 'harm or hurt; a wound or maim. Usually applied to damage inflicted to the body by an external force' (Dorland 1994); and the other definition is 'the damage or wound of trauma' (Stedman 1995). Again, there is no allusion to this being a form of disease. Trauma, in turn, is defined as 'a wound or injury' (Dorland 1994), or as 'an injury' (Stedman 1995). Now, let us think about all of this, critically. Let us first think of a baby that is born, tragically, with a severe case of neural tube defect or ventricular septal defect; and let us imagine asking the doctor, or the parents, whether the baby is healthy or has, instead, some condition of ill-health, illness. The answer obviously would indicate that the baby is not healthy but ill, has an illness. A follow-up question might be: do you mean that the baby has a congenital disease? The answer likely would deny this, pointing out that the baby has a malformation, a defect (congenital, macroanatomic), not a disease. Let us next imagine moving from the neonatal intensive care unit to the office of a surgeon who had just operated on the injuries of a car-accident victim. Asking the surgeon whether the victim is healthy or in a state of ill-health, illness, would likely draw a reaction of considerable puzzlement: the trauma surgeon does not presume to operate on healthy people, nor does (s)he think that surgery provides immediate restoration of health. Furthermore, asking what kind of disease did the accident victim have would likely be equally strange to the surgeon: (s)he understands that the case of illness was one of injuries, not disease. So, given that illness rather than disease actually is the overall concept of ill-health, and that a distinction is to be made between disease and defect as two broad types of illness, what distinguishes between them? It is really quite straightforward, we think, ingrained in the medical mind. A disease is defined by a process-type anomaly (as its proximate genus). It thus is prone to have a dynamic, evolving course; and one indeed commonly speaks of 'the disease process'. A defect, by contrast, is a more or less static, non-process-type anomaly. It thus is prone to have a quite stable course; and therefore, one does not speak of 'the defect process'. Significantly, one has been prone to speak of 'mental illness' and not of 'mental disease' or 'mental defect'– presumably as there has been no concept of the nature of the underlying somatic anomaly, whether it is process-type or static. (These days the term tends to be 'mental disorder' in lieu of 'mental illness'.) Then, what distinguishes both disease and defect from injury? The correct answer seems to be that both disease and defect have a pathogenesis of the ordinary, gradual, 'natural' sort – a matter of a somatic process in the tissue in question leading to the illness-defining anomaly in it – whereas in injury pathogenesis in this meaning is replaced by a sudden, extrinsic infliction. Upon its abrupt, extrapathologic inception, the 'natural' course of an injury is akin to that of a disease: 'dynamic' rather than static, with complications and sequelae, and fatality just the same, as its possible consequences. While the distinctions among disease (Latin morbus), defect (Latin vitium) and injury (Latin/Greek trauma) are fundamental to any taxonomy of illness (German Krankheit, French maladie), not all illnesses are now readily classifiable in these terms. While, say, malignant neoplasms and infectious diseases obviously are diseases (by the nature of their respective illness-defining anomalies) and congenital malformations as well as 'inborn errors of metabolism' obviously are defects (by the same criterion), what about illnesses such as malignant hypertension, glaucoma, cardiac arrhythmias, endocrine abnormalities such as hyper- and hypothyroidism, and adult-onset (type II) diabetes?; or, are these illnesses to begin with? In any attempt to clear such confusion, the necessary beginning is sharp distinction-making between the illness-defining somatic anomaly on one side and the potential manifestations of this (especially to the person at issue, in sickness) on the other side. To take an example, let us think of adult-onset diabetes as to whether it is a disease or a defect, or not an illness of any kind. Diabetes, consonant with the etymology of the word, is defined as high output of urine, polyuria (Dorland 1994; Stedman 1995). Thus, adult-onset diabetes one would reasonably presume to be polyuria (proximate genus) beginning in adulthood (specific difference) – not an illness nor even inherently a manifestation of illness (as, e.g., beer aficionados well know). In point of fact, though, the concept of adult-onset diabetes now is that of non-insulin-dependent diabetes mellitus (Dorland 1994; Stedman 1995). The concept of diabetes mellitus one might presume to be that of ample-and-sweet urine, but this literal interpretation of the term would again be at variance with the actually prevailing concept: 'a chronic syndrome of impaired . . . metabolism owing to insufficient secretion of insulin or to target tissue insulin resistance' (Dorland 1994); or 'a metabolic disease in which . . . ; it is caused by an absolute or relative deficiency of insulin . . .' (Stedman 1995). So, the concept of adult-onset, or type II, diabetes is now defined to be a 'syndrome' or 'disease' of metabolism, 'owing to' or 'caused by' insulin resistance of tissues; definitional to it is taken to be the metabolic abnormality rather than the cellular anomaly that this reflects. For what is at issue here, adult-onset diabetes is a misnomer. The metabolic syndrome to which this term refers, like any syndrome in proper terms, is not a 'disease' (meaning illness) but a manifestation of the properly illness-defining anomaly; and the underlying anomaly for a syndrome may be unknown, while here it is insulin resistance of tissues. This somatic anomaly, properly definitional to the illness, is not thought of as a process but as a defective state (usually emerging in adulthood). Thus, the misnomered illness is misclassified when thought of as a disease rather than a defect. The other examples above, upon similar critical examination, can also be classified. 'Hypertension' is a misnomer for high ('elevated') blood pressure; and the latter, however malignant, is not an illness of any kind but, again, merely a manifestation of (a non-sickness sign pointing to) an underlying defective state, high vascular resistance. Glaucoma, as a matter of pressure, is the intraocular counterpart of this, fundamentally a state of high outflow resistance for the intraocular fluid (cf. high resistance to cardiac output in hypertension). Cardiac arrhythmias are manifestations of illness-defining, and commonly unknown, anomalies of the rhythm-regulating system, not so much processes as defective states of this. Endocrine abnormalities generally are states of hyper- or hyposecretion, definable only on this level of defective state, not process, of glandular functionality, and thus not definable with reference to a 'deeper' anomaly. Type I, insulin-dependent diabetes (mellitus) is an example of this, having to do with the functionality of the islets of Langerhans; and on this level of definition it is an illness – a defect rather than a disease – while its associated metabolic and other abnormalities are but manifestations of this defect (cf. above). Insofar as, say, 'hypothyroidism' is a proper term, the proper counterpart for 'insulin-dependent diabetes' might be 'hypoisletism'. Whereas the classification of illnesses as diseases, defects and injuries is fundamental in the sense of the broadest nature of the illness-defining anomaly – having to do with the distinction between anomalous processes (dynamic) and defective states (static) among ones of pathogenetic origin and the distinction between both of these and exogenously inflicted sudden derangements – there are various other 'axes' of broad classification just the same. Traditional and still dominant among the latter in clinical medicine is classification according to the 'system' at issue: cardiovascular, endocrine, etc.; and in community medicine, equally eminent has been and still is the classification of illnesses as infectious or non-infectious, or as communicable or non-communicable, depending on whether at issue is aetiology or the possibility of person-to-person transmission. (Congenital heart defect, e.g., can be of infectious aetiology; but it never is communicable.) In both clinical and community medicine, a major distinction is made between acute and chronic illnesses; but remarkably, 'acute' is said to refer not only to short duration but also to the illness being severe (Dorland 1994; Stedman 1995). ('Acute myocardial infarction' can be 'silent', even; and, its chronic counterpart is unheard of.) Given that medicine is, in all essence, about illness, a major concern in scientific medicine is the development and adoption of logically tenable concepts of illness; and as in intellection in general, the next concern is to develop and adopt tenable classifications, taxonomies, of the generic entity of interest, here of illness. In both respects, the status quo remains less well developed than it should be.

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.