Executive Dyscontrol of Learning and Memory: Findings from a Clade C HIV-positive South African Sample

Abstract

Objective: Although pre-clinical work suggests there might be differences in neurovirulence across HIV-1 clades, few studies investigate neuropsychological deficits in the globally predominant clade C infection. The purpose of this study was to investigate verbal learning and memory performance in HIV-positive individuals in Cape Town, South Africa, where clade C is the most prevalent subtype of the virus. Method: Using a case-control design, we recruited 53 isiXhosa-speaking, cART-naïve HIV-positive adults and 53 demographically matched HIV-negative controls. Participants were administered a comprehensive neuropsychological test battery. The test of interest was the Hopkins Verbal Learning Test-Revised (HVLT-R); previous studies have used that instrument to identify executive dyscontrol of verbal learning and memory processes in clade B HIV-positive participants. Results: HIV-positive participants showed only partial impairment on the HVLT-R’s learning/memory components (e.g., they recalled significantly fewer words across learning trials, but displayed relatively intact performance on delayed recall trials). They also displayed little executive dyscontrol over encoding and retrieval processes (e.g., there were no significant between-group differences on measures of semantic or serial clustering). Conclusions: Post-cART era studies suggest that verbal learning and memory performance is impaired in clade B samples, at least partially due to executive dyscontrol over encoding and retrieval processes. We found few such impairments in the current clade C sample. These preliminary findings suggest different CNS vulnerability across clades that would have implications for delineating clade-specific neuropathological and neurocognitive clinical features.

Keywords:

• Clade C
• Executive dyscontrol
• HIV
• Prefrontostratial circuitry
• Verbal learning and memory.

Acknowledgments

We are grateful to Doris McEwan, Lorraine Adendorff, and Tebogo Linda for recruitment and technical assistance.

Notes

¹ The overall trends reported in Table 2 remained consistent after we removed the six HIV-negative participants with GDS ≥.5 and re-analyzed the data.

Additional information

Funding

This work was supported by the US President’s Emergency Plan for AIDS Relief (PEPFAR) through USAID [674-A-00-08-00009-00] to ANOVA Health Institute [JWT]; the South African National Research Foundation [JAW, KGFT, JAJ]; the Medical Research Council of South Africa [JAJ]; the Health Sciences Faculty of the University of Cape Town [JAJ]; and the Biological Psychiatry Special Interest Group of the Society of Psychiatrists [JAJ]. The views expressed in this paper do not necessarily reflect those of USAID/PEPFAR.