Gene expression of BDNF and NURR1 mRNA in the midbrain was found to negatively correlate with duration of illness in schizophrenia cases, and this may reflect that both mRNAs are known to decrease with age [101, 102], and the effect of increasing age on the brain may be more accelerated in schizophrenia [103, 104]. This evidence concerns the gene NR4A2 and schizophrenia.