The case for biology in the aetiology of anorexia nervosa.

It is now common to view anorexia nervosa as a multi-determined syndrome in which physical, psychological, family and sociocultural factors interact to produce the illness. Such a compromise position is difficult to refute. However, the components of this complex model neither explain nor account for the epidemiological and clinical features of the condition. A popular cultural thesis is that the victim of anorexia nervosa is struggling to change her body in an attempt to deal with the contradictory requirements of the female role in late twentiethcentury Western societies (Chernin, 1986; Orbach, 1986; Edwards, 1987). However, this thesis cannot account for the numerous clear descriptions of the condition which date from the middle of the nineteenth century (Marce, 1860; Gull, 1873; Lasegue, 1873), or even earlier (Morton, 1694). A common assumption held by many who argue for the importance of socio-cultural factors, is that there have been marked increases in the incidence of anorexia nervosa, over the last two or three decades. The evidence that anorexia nervosa, as opposed to bulimic disorders, has increased in incidence in parallel with the vast social changes of the last two centuries is, however, controversial. Although there is no doubt that case registers show an increase in anorexia nervosa over the last few decades (Kendell et al. 1973; Jones et al. 1980; Szmukler et al. 1986; Willi et al. 1990) this is probably an artefact, due to increased awareness of the condition and recognition of its psychological basis. When rigorous case-finding procedures were used (Lucas et al. 1988) no significant trends in incidence were found in the 45 years spanning from 1930 to 1979, although in a later paper which included the years 1980-5 a twofold increase in 15-24-year-old females was found (Lucas et al. 1991). The vivid case descriptions of anorexia nervosa in Hong Kong (Lee, 1991) serve to remind us that the form of the illness does vary between cultures; 'fear of fatness', in particular, is not universal. It was argued, at the NIMH-sponsored conference on cultural issues for DSM-IV, that anorexia nervosa can be found in developing countries if this criterion is omitted (Littlewood, 1992). At the same conference the proposal to classify anorexia nervosa as a 'culture bound' category was rejected. It is possible that the prevalence of anorexia nervosa is reduced in non-Western cultures but definitive studies have not been performed; rather, there has been a large series of case reports (from Asia: Buhrich, 1981; Ong et al. 1982; Kope & Sack, 1987; Khandelwal & Saxena, 1990; Gandhi et al. 1991, and Africa: Nwaefuna, 1981; Buchan & Gregory, 1984) and within ethnic minorities (Africans/USA/Caribbean/UK: Jones et al. 1980; Pumariega et al. 1984; Silber, 1984; Robinson & Anderson, 1985; Thomas & Szmukler, 1985; Holden & Robinson, 1988) and Asians: Bryant-Waugh & Lask, 1991; Mumford et al. 1991). Family models of aetiology have inspired new approaches to treatment of anorexia nervosa in the last decade. Abnormal family interactions have been observed but whether these are either causal or specific is far from certain (Humphrey et al. 1986; Kog & Vandereycken, 1989). An important deficit in both the familial and cultural models is the failure to account for individual susceptibility, which leads in some to the development of anorexia nervosa in the context of general environmental hazards. A biological model of the aetiology of anorexia nervosa, although currently out of fashion, is not new (Russell, 1970). In the early part of the twentieth century there was diagnostic confusion between pituitary insufficiency and anorexia nervosa (McCullagh & Tupper, 1940; Escamilla & Lisser, 1942). Later, the hypothalamus was implicated in the origin of anorexia nervosa following