It is likely that the interaction between appetitive brain regions and specific prefrontal cortex (PFC) cognitions determines whether an adolescent develops anorexia nervosa. We aim to provide neuropsychological and brain imaging measures showing how a specific cognitive function is linked to early-onset disordered eating behaviour, and we will do this before and after standard clinical treatment. We suggest that such understanding could enable school nurses to use the unique paradigm we use in our fMRI study, to detect illness before it damages the child's life and becomes difficult to treat.