DNMT1 and Cognitive impairment: For instance, in recent preclinical studies, sevoflurane and isoflurane anesthetics were reported to upregulate the DNMT3A, 3B, and DNMT1 gene expression respectively, resulting in hypermethylation of BDNF and Reelin genes, resulting in synaptic plasticity deficiency and thereby leads to cognitive impairment [31,32].