Speed of memory scanning is not affected in early HIV-1 infection

Thirty-seven nondemented HIV-seropositive and 17 seronegative control subjects were administered the Sternberg speed of memory scanning task, a procedure frequently employed to study mental slowing in patients with subcortical dementing disorders. Experimental and control subjects did not differ in speed of memory scanning, as indexed by the slopes of set size-reaction time functions, nor on mean 0-intercepts for the RT functions, which index stimulus detection and motor response time. Intercept values were significantly greater for subjects with a positive alcohol abuse history and for subjects with greater self-reported depression, but slopes were not significantly correlated with substance abuse history or psychological distress. Cognitive slowing in early HIV-1 infection is not a nonspecific effect observed across all measures of information processing speed. Underlying component functions measured must be carefully considered when selecting reaction time tasks for study with HIV-seropositive subjects. The term "subcortical" dementia may be too general a descriptor, and RT task performance may provide an alternative basis for classification of dementia types.