Children with symptomatic HIV-1 (Human Immunodeficiency Virus) infection are at increased risk for developing severely disabling neurological and neuropsychological deficits. HIV-1 related CNS (Central Nervous System) disease is a clinical syndrome, manifested by varying and sometimes discordant degrees of cognitive, motor and behavioral impairment. A continuum of clinical presentations attributed to the effects of HIV-1 infection on the CNS, ranging from apparently normal development, decreases in the rate of new learning to the loss of acquired skills have been observed. Two domains of psychological functioning appear most susceptible to the effects of HIV infection on the central nervous system in children: expressive behavior and attentional processes (Brouwers, et al, 1994).

Attention deficits have been documented as a relative weakness on the "freedom from distractibility" subclass of IQ tests (Brouwers et al, 1989) and on behavior assessment (Moss et al, 1994). Attention, however, has many subcomponents such as focused attention, divided attention, vigilance, etc. Direct assessment of attentional functioning using reaction time has not yet been conducted and questions whether attentional components are differentially affected by the virus have not been addressed.

The proposed study would assess different components of attentional functioning in children with HIV-1 disease. A quantitative and systematic method is developed that could complement the existing standardized instruments used for measuring attention and neurocognitive function in this population. Simple alerted visual reaction time will be measured with varying preparatory intervals, a two-choice reaction time in a go/no-go paradigm will be administered, and a continuous performance, divided reaction time test and an object decision task will be given. Performance on these measures will also be related to measures of brain structure and stage of HIV-1 disease.