Background: The CNS is an important target of HIV-induced injury. We have used an aggregate mean normalized score on 4 relatively simple quantitative tests of neurological performance, the QNPZ-4, to monitor a longitudinal (sentinel) neurological cohort (SNC). We now report on the changes in this score over 1 year of subject follow-up.

Methods: The SNC subjects were segregated into 3 groups based on treatment status and plasma (and CSF) HIV concentrations at study entry:  groups S (successes) on antiretroviral therapy (ART) with plasma or CSF viral loads (VL) <500 copies/mL; F (failures) on ART with plasma or CSF VL >500 copies; and N off therapy (no ART). Subjects were reassessed at 4, 8, and 12 months after baseline for plasma and CSF VL, blood CD4 and CD8, CSF cell count, and other clinical and laboratory parameters. QNZP-4 testing was also performed at these intervals. This score is the average of the normalized (for age and education) scores on 4 tests:  timed gait, Digit-Symbol from the WAIS-R, finger tapping (non-dominant hand), and grooved pegboard (dominant hand); by definition normal performance = 0.00 with SD = 1.00.

Results.   A total of 122 subjects (F = 32; S = 45, N = 45) were enrolled. At baseline, QNPZ-4 scores were below controls (mean +SD:  total cohort = -0.61+1.23), similar in the 3 groups (S = -0.46+1.14; F = -0.67+1.44 ; N = -0.72+1.17; no significant differences by ANOVA), and correlated only with the blood CD4 count (p = 0.018) among the measured baseline variables. For those subjects followed at 1 year (n = 73: S = 37, F = 18, N = 18) the change in QNPZ-4 was similar for all 3 groups (mean+SD change: total group = 0.23+0.67; S = 0.24+0.59; F= 0.19+0.61; N = 0.24+0.88). However, across the 3 groups the change in QNPZ-4 correlated inversely with the CSF VL at 1 year (Spearman’s r = -0.382, p = 0.0034) and directly with changes (decreases and increases) in the blood CD4 and CD8 cell counts from baseline (r = 0.381 and 0.428, p = 0.0008 & 0.0001, respectively).

Conclusions:  Overall, neurological function in the cohort, as assessed by the QNPZ-4 score, improved slightly over 1 year without a clear difference among the 3 groups. However, the course of HIV infection (as indicated by CSF HIV concentrations at 1 year and changes in T-cell counts) was associated with changes in neurological performance across the entire cohort.

Keywords: neurological; CSF; treatment