Immunological disturbance and infectious disease in anorexia nervosa: a review

Objective: Severely malnourished patients with anorexia nervosa (AN) are reported to show fewer symptomatic viral infections and a poorer response to bacterial infection than controls. They are also reported to show mild immune system changes, although the relevance of these to altered infection disease presentation in AN and AN pathophysiology is unknown. Thus, in this paper, we suggest a range of immune system changes that might underpin these altered responses to common pathogens, and review a number of recent infectious disease findings for their utility in explaining the pathophysiology of AN. Methods: A systematic review of the literature pertaining to immunity and infectious disease in AN was performed. Results: AN is associated with leucopenia, and the increased spontaneous and stimulated levels of proinflammatory cytokines [i.e. interleukin (IL)-1 beta, IL-6 and tumour necrosis factor alpha). A range of less consistent findings are also reviewed. Most of these data were not controlled for length of illness, degree of malnutrition, micronutrient or vitamin deficiencies or recent refeeding and starvation. Conclusion: Cytokine disturbances have been suggested to be causally related to AN symptomatology and pathophysiology of AN, although the evidence supporting this assertion is lacking. Immune and cytokine changes in AN do, however, occur in association with a decreased incidence of symptomatic viral infection, decreased clinical response to bacterial infection leading to delayed diagnosis and increased morbidity and mortality associated with the infections.