Moreover, low BDNF circulating levels have also been reported in other chronic mental disorders, including obsessive-compulsive disorder, major depression, bipolar disorder, and schizophrenia (Bocchio-Chiavetto et al., 2010; Fontenelle et al., 2012; Brand et al., 2015; Fernandes et al., 2015), reasonably pointing to BDNF as a potential biomarker of increased vulnerability also in AN. This evidence concerns the gene BDNF and obsessive-compulsive disorder.