Dementia is a syndrome caused by brain diseases,which can be seen in Alzheimer's disease,cerebrovascular disease,and other conditions that damage the brain.The ICD-10 disease codes involved are different.In practice,due to incomplete collection of medical records,dementia syndrome coding often appears incorrect.By selecting cases,coding analysis is performed for different types of dementia,and additional coding is used to indicate the underlying disease,involving codes such as G30.8†F00.2*,G30.0† F00.0*,G30.l† F00.1*,F01.2,F01.1,F01.0,A52.l†F02.8*,pointing out the easy-to-make mistakes in coding and the difficulties in diagnosis.The difference between the different stages of Alzheimer's disease dementia and vascular dementia is a difficulty,followed by the situation when the two diseases coexist,and in addition,the coding rules for other diseases causing dementia classified elsewhere also need attention.Coders must not only carefully review medical records but also widely solicit the opinions of attending physicians,follow the diagnostic descriptions provided by physicians,and obtain correct dementia coding through comprehensive analysis.