Reaction time performance in adults with HIV/AIDS

Abstract

Infection with the Human Immunodeficiency Virus-Type 1 (HIV-1) has been shown to lead to cognitive decline in a substantial proportion of infected adults. The characteristic neuropsychological symptomatology includes memory dysfunction, higher order attentional disturbance, executive dysfunction and, most relevant to this manuscript, cognitive slowing. This paper reviews the extant literature on reaction time (RT) performance in HIV-infected adults with an emphasis on mental chronometry. In addition to discussing studies of simple and choice RT, we also examine the utility of RT paradigms in the assessment of selective attention, covert orienting, sustained attention, divided attention, working memory, and implicit memory. Studies documenting the utility of RT tasks to track treatment response are also introduced. In aggregate, research to date that has employed RT tasks in the evaluation of HIV-infected patients has found that HIV infection leads to a mild degree of cognitive slowing that tends to worsen with increasing disease severity. It needs to be noted, however, that a significant percentage of studies failed to find HIV infection to lead to RT slowing. Results of Brinley plot analyses, a technique that shares commonalities with meta-analysis, reveal that HIV-infected patients diagnosed with AIDS are on an average 22% slower than uninfected controls. This paper also reviews data that has shown that HIV associated cognitive slowing, as indexed by single and dual choice RT, is amenable to pharmacologic intervention using the psychostimulant methylphenidate. Given the demonstrated sensitivity of RT tasks to the neuropsychological effects of HIV infection, it is recommended that RT tasks be included whenever possible in the routine clinical evaluation of HIV-infected patients.