Anorexia nervosa (AN) is a psychiatric illness that commonly arises during adolescence. Among all the psychiatric disorders anorexia has the highest mortality rate and it is associated with severe medical morbidity . Regard to complications, heart abnormalities , osteopenia , endocrine alterations and brain abnormalities are common.
The typical hypothalamic amenorrhea is associated with low serum levels of gonadotropins and sexual hormones. Plasmatic levels of leptin, a peptide produced by fat store and involved in appetite-regulating mechanisms, are also reduced. GH (growth hormone) levels are often increased accompanied by low levels of IGF-1 (insulin-like growth factor) which suggests an acquired peripheral resistance to GH. An hypercortisolemia is common to almost all women with AN, but not associated to the typical Cushingoid features and often not suppressible after dexamethasone administration. Abnormalities of the thyroid axis are also relevant and characterized by low levels of T3 (triiodothyronine), whereas T4 (thyroxine) and TSH (thyroid stimulating hormone) are normal or slightly reduced [4, 5].
Previous neuroimaging studies on AN showed global gray (GM) and white matter (WM) reduction and an increase in cerebrospinal fluid volumes (CSF) [6, 7], while other authors didn’t confirm GM [8, 9] or WM decrease .
In literature, associations between brain alterations and hormonal profile changes as hypercortisolemia [6, 11, 12] and low levels of T3[12–14] are described.
Weight restoration tends to improve brain abnormalities in AN, but it is still not clear whether reversibility is complete [6, 8, 10, 15, 16]. Etiopatogenetic mechanism of cerebral alterations are not still completely explained. First hypothesis that volume reductions are related to neuron death has not been confirmed either by neuro-biochemical , histological studies  or by improvement of brain alterations with weight restoration . The current hypothesis, summarized in Swayze’s study , include: i) decreased serum proteins resulting in decreased colloidal osmotic pressure and a shift of fluid from the intravascular space into the subarachnoid spaces ; ii) partial regeneration of damaged neurons and their axons with possible regeneration of myelin ; iii) loss of lean body tissue mass ; iv) increased urine and serum cortisol levels ; v) decreased protein synthesis resulting in loss of dendritic spines, a reduction in the number of synaptic junctions, and delayed synaptogenesis .
In literature associations between brain volumes and BMI in AN are known , anyway no study explored the impact of speed and magnitude of weight loss on cerebral trophic changes in adolescents with anorexia nervosa. The purpose of our study is to examine this correlation and its implications in the clinical treatment of these young patients.