Memory performance in HIV/AIDS - A prospective case control study

Background: Memory impairment, usually impaired retrieval of information, has been described in HIV/AIDS, especially among those with severe illness. Neuro-cognitive disturbances in HIV/AIDS have been linked to poor quality of life and medication adherence. This prospective, case-control study was designed to assess the verbal and non-verbal memory as well as the attention abilities of Nigerian Africans with HIV/AIDS and correlate their performances with their CD4+ T lymphocytes (CD4+) counts. Methods: A total of 288 randomly selected subjects, comprising 96 HIV-positive symptomatic patients, 96 HIV-positive asymptomatic patients and 96 HIV-negative controls, participated in the study. The subjects were age-, sex-, and level of education matched. The Recognition Memory Test and Choice Reaction Time tasks, components of the computer-assisted neuropsychological tests battery- the Iron Psychology 'FePsy' were used for cognitive assessments. Results: The mean memory scores of the HIV-positive asymptomatic subjects did not differ significantly from the controls (p>0.05) but the HIV-positive symptomatic subjects' scores were significantly lower than the controls (p<0.05). Both HIV-positive groups had psychomotor slowing and impaired attention (p<0.05). The HIV-positive subjects with CD4+ counts <200/μl and between 200 and 499/μl had significant memory impairment (p<0.001 and p<0.001 respectively) but there was no significant impairment among those with count ≥500/μl. Impaired ability for sustained attention was however present irrespective of the CD4+ level relative to controls (p<0.001). Conclusions: We concluded that there was no significant memory disturbance among HIV-positive asymptomatic subjects despite the presence of impaired attention and psychomotor slowing, and that the severity of immune suppression (as indicated by the CD4+ T lymphocytes count) is a strong determinant of cognitive decline in HIV/AIDS.