At the other end of the spectrum, the HIV-infected controls had the lowest proportion with IHDS < =10 (66%), the lowest depression scale scores (CES-D: 9, IQR: 5–17), highest Karnofsky performance score (90, IQR: 90–90), and significantly higher median CD4 counts (233 cells/μL, IQR: 183–297) compared with the other two study populations. This evidence concerns the gene CD4 and major depressive disorder.