Abstract: Objective  To investigate the relationship between trimethylamine N-Oxide(TMAO) and mild cognitive impairment (MCI)in young and middleaged patients with maintenance hemodialysis(MHD). Methods  Totally 108 cases of young and middleaged MHD patientsadmitted to the hospital from June 2016 to June 2018 were selected as subjects. Simple intelligence state examination scale and Montreal cognitive assessment(MoCA) scale were used to evaluate patients' cognitive function, and investigate the clinical data and laboratory indicators of selected patients, TMAO levels were measured by highefficiency liquid chromatography series mass spectrometry, and the correlation between TMAO and MCI was also analyzed.Results  Among 108 young and middleaged MHD patients, totally 50 cases suffered from  MCI,which was accounted for 46.3%.  Compared with the nonMCI group, the proportion of male, dialysis age, combined diabetes, TG, LDL, UA, CRP and TMAO were higher, the proportion of middle school patients above the education was lower(P<0.05). MoCA integrals were negatively correlated with dialysis age, diabetes, and TMAO, and they were positively correlated with educational attainment (r=-0.402, -0.216, -0.416, 0.389, P＜0.05).   The elderly, long dialysis age and  increase of TMAO were independent risk factors for the occurrence of MCI in young and middleaged MHD patients, while the high education level was a protective factor.Conclusion  The incidence of MCI was higher in young and middleaged MHD patients, and the increase of  TMAO was an independent risk factor for MCI.

Key words: renal , dialysis；mild , cognitive impairment；trimethylamine NOxide