In the past, lower serum BDNF levels in patients suffering from a number of neurological conditions compared to HC have been reported (such as depression,31 schizophrenia,32, 33, 34, 35, 36, 37, 38 Alzheimer’s,39, 40 or Huntington’s disease.41, 42. This evidence concerns the gene BDNF and schizophrenia.