CD4 and Cognitive impairment: This comprehensive model incorporated 10 variables: serum creatinine and chloride levels, the percentage of peripheral blood CD4+ICOS+ and CD19+PD-L1+, plasma soluble inducible costimulatory ligand (sICOSL), cerebrospinal fluid (CSF) glucose content, and the presence of fever, nausea, vomiting, headaches, and cognitive impairment.