Objective To evaluate the value of intrathecal synthetic related markers in patients with mild cognitive impairment(MCI),Alzheimer's disease(AD),and other types of dementia.Methods Retrospec-tively collect the clinical data of 577 patients diagnosed with MCI(MCI group,178 cases),AD(AD group,131 cases),and other types of dementia(other types group,268 cases)from June 2019 to July 2023 in Beijing Tiantan Hospital,Capital Medical University.Oligoclonal zone electrophoresis(OCB)and 24 h intrathecal pro-tein synthesis rate(ISR)of each group were investigated,and the difference of different indexes among the groups was compared to evaluate the value of related indexes in the differential diagnosis of different diseases.Results Compared with AD group and other groups,AD group had a higher proportion of females,more patients were＞50-70 years old,and the incidence of abnormal lipid metabolism was higher,with statistical significance(P＜0.05).There were significant differences in OB(S),cerebrospinal fluid albumin,serum albumin and cerebrospinal flu-id IgG in different disease groups(P＜0.05).IgG index and ISR in patients with positive SOB(CSF)were higher than those in negative and weakly positive patients,and the differences were statistically significant(P＜0.001).IgG index was positively correlated with ISR(r=0.878,P＜0.001).Conclusion Intrathecal synthetic mark-ers such as IgG index,SOB(CSF)and 24 h ISR have synergistic effects in the diagnosis of cognitive dysfunction and various dementias,which can be collectively utilized in the diagnosis of diseases.