CD4 and Alzheimer disease: Approximately half of the new cases identified are diagnosed late, both in Spain (47.6% in 2018) and in the EEA (49.4%).[1,2] Late diagnosis (LD) is defined as the presence of a CD4 count <350 cells/μL in the first determination after HIV diagnosis, and advanced disease (AD) indicated by a CD4 count <200 cells/μL.