MD2, Cystatin C and DNA Methylation Tags as Serum Biomarkers for POCD.

Postoperative cognitive dysfunction (POCD) is a severe complication after surgery. Currently, a complicated battery of neuropsychological tests both before and after surgery with other characteristics-matched population as control are needed for the diagnosis of POCD. This diagnosis is also delayed, which could not be used to screen for high risk patients who may need intervention beforehand. The current trial targeted a surgical population of elderly patients undergoing cardiac surgery under cardiopulmonary bypass (CPB), which is a population of the highest incidence of POCD, to screen for possible predictive or diagnostic biomarkers in the serum for POCD. Myeloid differentiation factor 2 (MD2), also known as lymphocyte antigen 96, is a protein involved in biding lipopolysaccharide with Toll like receptor-4 (TLR4). Recently the investigators have found that increased MD2 expression in the hippocampus of the mice after surgery stimuli. On the other hand, the investigators have reported that cystatin C (CysC) as an endogenous neuroprotective factor for stroke. It may also be involved in endogenous neural protection against POCD. This trial is to investigate whether serum MD2, CysC can be used for prediction and diagnosis of POCD in surgical population. Serum based DNA methylation biomarkers will also be tested for prediction or diagnosis of POCD development. Also in our orevious research, SNPs cites at rs6739405、rs12467815、rs12472215、rs11126727、rs11126731、rs993607 were revealed as possible susceptibility variations for POCD (diagnosed with MMSE only, NCT02084030) in patients undergoing CPB. This study will also test the SNP variations in study populations to varify if one or conbination of morethan one of these varuations can be a risk factor for POCD when diagonosed with NPT.