HIV-1-associated dementia complex (HIV dementia) occurs in 20% of HIV- infected individuals and is characterized by cognitive, behavioral, and motor dysfunction. In particular, psychomotor slowing is one of the earliest neuropsychological indicators of the development of dementia. Functional MRI (FMRI) is a novel neuroimaging tool which provides maps of human brain activation with high spatial and temporal resolution. The technique is a noninvasive assessment of changes in regional cerebral blood flow in response to a specific cognitive task. Functional neuroimaging may detect subtle alterations in neurological function before clinical and structural abnormalities develop. Our study was designed to evaluate the FMRI activation pattern in response to a test of psychomotor speed in HIV-infected patients. Our hypothesis was that compared to HIV seronegative (HIV-) subjects, HIV seropositive (HIV+) patients with psychomotor slowing would have an abnormal FMRI pattern in the frontal cortex and basal ganglia in response to a test of psychomotor speed. To date, we have completed FMRI studies in 3 subjects, an HIV-control and 2 HIV+ subjects with psychomotor slowing. In response to a simple finger tapping task, the HIV- and HIV+ subjects demonstrated similar activation of the contralateral primary motor cortex. In response to a measure of sequential reaction time, the HIV- control demonstrated multiple areas of activation in the frontal cortex whereas the HIV+ subject demonstrated no activation in the frontal cortex. we are currently in the process of analyzing additional data and recruiting additional subjects to determine the validity of these preliminary results.
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