J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.27.4.277 on 1 August 1964. Downloaded from J. Neurol. Neurosurg. Psychiat., 1964, 27, 277 Epidemiology and mental disorder: A review MICHAEL SHEPHERD AND BRIAN COOPER From the Institute ofPsychiatry, the Maudsley Hospital, London Though it is now fashionable to speak of the demiology were in circulation before 1914, the year epidemiology of mental illness, this conjunction of in which Goldberger published the first of a series of terms appeared in the literature only rarely before papers which were to demonstrate beyond argument 1949, when it was chosen as the title of a conference the professional epidemiologist's contribution to the organized by the Milbank Memorial Fund to ex- study of mental illness. There were several well- plore common ground between psychiatrists and documented accounts of the so-called psychic epi- public health workers (Milbank Memorial Fund, demics. The development of intelligence testing and 1950). Since then a spate of publications, especially the early studies of suicide had established the value in North America, the Scandinavian countries, and ofthe ecologist's method; and the older psychiatrists, the United Kingdom, has signalized the confluence as Lewis has pointed out, were familiar with such of two medical disciplines. The number of these in- basic epidemiological themes as the relationship vestigations is now so large, and their nature so between mental disorder and migration, isolation, varied, that it is advisable to demarcate the bound- occupation, and socio-economic change (Lewis, aries of psychiatric epidemiology. In Britain this task 1962). has been made easier by the cataloguing of current In view of these promising trends, it is of more Protected by copyright. research projects by the M.R.C. Committee on the than historical interest to examine the reasons for the Epidemiology of Mental Disorder (Rawnsley, relative neglect of the mass aspects of mental dis- 1963a), itself only some four years old. Just over 100 order in the earlier part of this century. How well projects are listed, of which approximately one third the concepts of epidemiology had been established is are focused on the psychological and social aspects of clear from Frost's masterly review, published in mental illness, either causal or concomitant; about 1927, which summed up the thinking of his day one quarter, which includes genetic studies, are con- (Frost, 1927). Epidemiology, he wrote, being cerned with the incidence or prevalence of different '... essentially a collective science, its progress is forms ofpsychiatric morbidity; one sixth concentrate largely dependent upon that which has been made on prognostic or follow-up studies, and almost as in other fields. Since the description of the distribu- many on primarily administrative issues; the re- tion of any disease in a population obviously re- maining small miscellany comprises studies of diag- quires that the disease must be recognized when it nosis, vital statistics, and the evaluation of thera- occurs, the development of epidemiology must peutic procedures. follow and be limited by clinical diagnosis, and by These topics can be taken as representative of the the rather complex machinery required for the modern -view of the scope of the epidemiological systematic collection of morbidity and mortality method in psychiatry; they fit well, for example, into statistics. Epidemiology must also draw upon http://jnnp.bmj.com/ the outline sketched by Lin in his recent W.H.O. statistical methods and theory, because even the monograph (Lin and Standley, 1962). At the same simplest quantitative descriptions must be stated time. it is apparent that to call the majority of such statistically; and more minute descriptions, involving studies 'epidemiological' is, in one sense, to do little perhaps the demonstration of complex associations, more than attach new labels to old bottles: their may require the application of quite elaborate objectives have been among the legitimate goals of statistical technique. Moreover, quantitative epi- psychiatric research for over a century. Clearly, demiological descriptions, in terms of frequencies of some understanding of the evolution of psychiatric disease in different population groups, require, as on October 5, 2021 by guest. epidemiology is necessary if its present status and, part of their data, more or less detailed statistics of still more important, its future prospects are to be population, implying the prior development of assessed. demography.' Unfortunately, Frost's vision was partially HISTORICAL DEVELOPMENT blinkered by the conventions of his day, for he goes on: Many of our current notions on psychiatric epi- L. .. usage has extended the meaning of epi- 277 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.27.4.277 on 1 August 1964. Downloaded from 278 Michael Shepherd and Brian Cooper demiology beyond its original limits, to denote not its originator's interest in the social sciences and merely the doctrine of epidemics, but a science of construing mental illness as 'the reaction of a per- broader scope in relation to the mass phenomena of sonality (conceived as made up of constitutional diseases in their usual or endemic as well as their endowment plus experience) to a situation in the epidemic occurrences. Although it is clear from cur- social environment' (Leighton, 1951), might have rent usage that the definition of epidemiology has provided an acceptable theoretical system had it not been extended beyond its original sense, it is not been for the clumsiness of most psychobiological clear just how far it has been extended. It is certain formulations. At the same time, attempts to frame a that its scope is not usually limited to the diseases theory of group behaviour based on instinctual pro- in which epidemics are characteristic, since it is pensities (Trotter, 1942) became submerged by the entirely in conformity with good usage to speak of growing influence of Freudian psychology, and were the epidemiology of tuberculosis; and it seems to remain neglected until the contemporary renewal customary also to apply the term to the mass of interest arising from comparative ethology. In his phenomena of such non-infectious diseases as discussion of group psychology Freud gave lucid scurvy, but not to the so-called constitutional expression to the latent antithesis between his own diseases, such as arteriosclerosis and nephritis ... outlook and that of the social psychologist: 'In this sense epidemiology may be defined as the 'Group psychology is .. concerned with the science ofthe mass phenomena ofinfectious diseases, individual man as a member of a race, of a nation, or as the natural history of the infectious diseases.' or as a component part of a crowd of people who In as much as this definition would exclude most have been organized into a group at some particular mental illness from the purview of the epidemio- time for some particular purpose. When once natural logists, their disregard of psychiatry-with some rare continuity has been severed in this way, if a breach and distinguished exceptions-could be attributed to is thus made between things which are by nature the state of development of their subject. The failure interconnected, it is easy to regard the phenomena, oftheir leading psychiatric contemporaries to interest which appear under these special conditions as beingProtected by copyright. themselves in the mass phenomena of mental illness, expressions of a special instinct ("herd instinct", on the other hand, can be more readily explained in "group mind"), which does not come to light in any terms of professional priorities. Many psychiatrists other situations. But we may perhaps venture to were preoccupied with a set of biological and object that it seems difficult to attribute to the factor phenomenological concepts, hoping to establish a of number a significance so great as to make it scientific nosology with, in Adolf Meyer's words, capable by itself of arousing in our mental life a new 'the psychological facts in their patients as mere instinct that is otherwise not brought into play. Our symptoms of more or less hypothetical diseases back expectation is therefore directed towards two other of them' (Meyer, 1912). Yet to the more discerning possibilities, that the social instinct may not be a epidemiologists these 'psychological facts' were in- primitive one and insusceptible of dissection, and separably part of the mass phenomena of mental dis- that it may be possible to discover the beginnings of order; to Greenwood, for example, they figured its development in a narrower circle, such as that of prominently among his procatarcticfactors ofdisease the family' (Freud, 1955). and he wrote ofthem withcharacteristic hard headed- While this point of view does not preclude an ness: 'It is my business to point out that while a interest in the mass phenomena of disease, the of the of such of so fairly consistent description aetiology emphasis authoritative a theorist tended tohttp://jnnp.bmj.com/ crowd-diseases ... can be provided by means of the produce a concentration on individual psycho- hypothesis that the psychological element in the mix- pathology at the expense of a psychology of social ture of interactions expressed in bodily illness is the involvement. Indeed, as one sympathetic critic has determinant, methods which have ignored that ele- observed: 'Withcertain exceptions, social pyschology ment have led to no consistent account of the facts and psychoanalysis do not contradict each other- at all. For this severely practical reason I hold that they no longer speak the same language' (Brown, practical epidemiologists cannot afford to neglect 1961). Linguistic difficulties can be expected to im- What should is pair communication. It is psychology. psychology they study therefore not surprising on October 5, 2021 by guest. not for me to say.' (Greenwood, 1935). that misunderstandings arose between epidemio- Thirty years later, it is easier to appreciate that for logists and depth psychologists over questions of the epidemiologist, concerned primarily with the mutual interest.