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Relationship of CD4 counts to neurophysiological function in HIV-1--infected homosexual men
A A Boccellari1, J W Dilley, C D Yingling
1Department of Psychiatry, San Francisco General Hospital, CA 94110.
Objective:
To explore the relationship of immune dysfunction to neurophysiological measures of brain-stem conduction time.
Design:
Three-year longitudinal prospective cohort study; results of time 1 analyses reported.
Setting:
San Francisco (California) General Hospital, Departments of Psychiatry and Epidemiology.
Patients:
Volunteer sample of 55 human immunodeficiency virus (HIV)-positive and 37 HIV-negative homosexual men recruited from a larger cohort of homosexual men followed up since 1983 at San Francisco General Hospital as part of an ongoing study of the natural history and course of HIV type 1 infection.
Intervention:
None.
Main Outcome Measures:
Auditory brain-stem responses and somatosensory evoked potentials for subjects stratified separately on HIV serostatus, Centers for Disease Control and Prevention symptom groupings, and absolute CD4 counts.
Results:
The HIV-positive subjects had an increased wave III-V interpeak latency of the right ear auditory brain-stem response compared with the HIV-negative subjects (t test, P < .05). There were no significant differences among the three Centers for Disease Control and Prevention groupings on any evoked potential measure. When HIV-positive subjects were stratified on a measure of immune functioning, ie, CD4 counts, individuals with greater immune suppression were more impaired on speed of auditory brain-stem conduction time (Mann-Whitney U test, P < .05). Furthermore, 85% of subjects impaired on this evoked potential measure had CD4 counts of less than 0.40 x 10(9)/L (400/microL), whereas only 15% of those impaired on this measure had CD4 counts of greater than 0.40 x 10(9)/L.
Conclusions:
Asymptomatic HIV-positive subjects who do not have evidence of immune suppression do not appear to be at greater risk for neurophysiological impairment than HIV-negative subjects. The HIV-positive individuals who are immune suppressed (even while asymptomatic) appear to have an increased likelihood of central conduction time slowing as measured by evoked potential procedures.