In the cluster (in red in Fig. 4), “Sex difference in the association of body mass index and BDNF levels in Chinese patients with chronic schizophrenia”, the most important article was the one by Yang et al. [56], which focused on the needs to consider sex when assessing the relationship between BDNF and metabolic syndromes in schizophrenia. Here, BDNF is linked to schizophrenia.