Dr. Clifford discussed results of the Ethiopian Netherlands AIDS Research Project (ENARP), a longitudinal natural history study of HIV in two communities in rural Ethiopia where general healthcare is available (Clifford, 2006).
HIV assessments were performed at each of the communities in this cohort as a part of the Ethiopian Neurologic AIDS Research Consortium. (ENARC) (Clifford et al, 2007). Both HIV positives and controls came from the same community, and all HIV positives available were studied. The investigators also evaluated a new rapid screening measure for dementia called the International HIV Dementia Scale (IHDS). Patients were given four tasks: naming four objects, fingertapping, the “Luria” psychomotor learning task, and a delayed recall of the four objects previously named. The IHDS revealed no significant differences between the control population and the HIV-affected population. However, the traditional testing, largely using motor speeded tasks, did reveal significant slowing of finger tapping in the HIV-affected group, whereas all other tests showed no difference. The investigators detected less HIV-associated disability than was anticipated for this study. Performance of both controls and HIV positives were impaired by Western standards, but did not significantly differ from each other. The IHDS did not demonstrate differences between HIV positives and negatives consistent with clinical impression. Neuropathy was found in approximately 15% of both positive and negative populations.
Compared to the Ethiopian project, the untreated population from the Ugandan clinic showed more cognitive impairment, as well as more advanced CD4/Karnofsky status. However, population differences as well as study design could explain disparities in the results. Researchers emphasized that norms for tests must be developed locally and require an appropriate normal population. Examination conditions and examiners should be the same for HIV+ and control populations. Demographic influences may be meaningful and unrecognized; thus, populations should be well matched. It is also possible that the genetic diversity of different viral subtypes could play a part in the disparity seen in different populations (Liner et al, 2007; Sacktor et al, 2007). Although this has been inadequately studied, there have been several recent reports that HIV subtype D is associated with faster disease progression, specifically over subtype A (Kaleebu et al, 2002, 2007; Kanki et al, 1999; Vasan et al, 2006). With subtype C predominant in Ethiopia and subtype D predominant in Uganda, regional differences in disease progression could be a result of the genetic diversity of different viral subtypes. Unfortunately, the relative neurovirulence of different subtypes is not well known.
Read the full article from NIH: Excerpt from the article, Second Assessment of NeuroAIDS in Africa