Both lower nadir CD4+ T cell count and occurrence of an AIDS illness have also been identified as risk factors for the development of HAND in both the pre- and post-ART eras, suggesting that despite successful viral suppression and at least partial restoration of immune function with ART, there may be a persistent immune dysfunction contributing to the development of cognitive impairment in some PLWH [93,110,111]. Here, CD4 is linked to immune system disorder.