Anorexia nervosa and the insula.

Anorexia nervosa is a serious illness with major physical and psychological morbidity. It has largely been understood in terms of cultural and environmental explanations. However these are insufficient to explain the diverse clinical features of the illness, nor its rarity given the universality of sociocultural factors. Over the last 20 years, there has been a steady accumulation of neurobiological evidence requiring a re-formulation of current causal models. We now offer a new empirically-derived hypothesis implicating underlying rate-limiting dysfunction of insula cortex as a crucial risk factor for the development of anorexia nervosa. Supporting evidence for this hypothesis is drawn from anatomical and clinical research of insula cortex damage in humans and neuroscientific studies of relevant clinical features including taste, pain perception and reward processing. This hypothesis, if sustainable, would be the first fully to explain the disorder and predicts promising novel treatment possibilities including Cognitive Remediation and Motivation Enhancement Therapies. The knowledge that the challenging behaviours, so characteristic of AN, are the result of underlying cerebral dysfunction, rather than being purely volitional, could help to reduce the stigma patients experience and improve the therapeutic alliance in this poorly understood and difficult to treat disorder.