Capturing the anorexia nervosa phenotype: Conceptual and normative issues in ICD-11.

Abstract

ICD-11's diagnostic definition possesses conceptual lacunae and normative implications calling for further attention. Assumptions underlying it and their ethical implications, are examined employing philosophical analysis; particularly, these are (1) changes to eliminate implications of voluntary agency to caloric restriction; (2) definitions of "dangerously low weight;" and (3) disorder boundaries as stated in qualifications and exclusions. (1) The extent to which AN behaviour can be acknowledged to be driven by forces out of, or limiting, voluntary control is unresolved; this is illustrated using the contested part played by excessive exercise, clarification of which requires understanding of AN motivation. (2) AN's uncertain aetiology leaves doubt over the sub-threshold state. This affects not only when treatment is appropriate, but how definitions of morbidly low body weight are determined, putting individuals with prodromal symptoms at the social risks associated with "medicalizing" normal variation. Concluded here is not that ICD-11's conservative definition is mistaken but that since false positives are common, they must be factored into the complex cost-risk assessments involved. (3) ICD-11 efforts to minimize reliance on subjective motivation reveal limitations in exclusion criteria. Were AN motivation itself better understood, it would be possible to deal with non-anorexic motivation by exclusion. But the history of "fat fears" illustrates that uncertainty attaches to interpretations of AN motivation. Neither AN motivation nor cultural norms around other forms of self-starvation admit of clear characterization, leaving an impasse. At least with present day medical and scientific knowledge, a complete characterization of the AN phenotype cannot be achieved without reference to psychological states of motivation. And more research, not only clinical, genetic and neurobiological but also conceptual and ethical, will be required to resolve the challenges presented by AN.