Imaging studies detect very early brain changes in HIV.
Significant increases in lactate, a marker of anaerobic glycolysis, and lipids, a marker of oxidative stress, on magnetic resonance spectroscopy (MRS) may be the earliest signs of HIV-related impairment in the brain, with important implications for treatment, said Dr. Ances of the HIV Neurobehavioral Research Center at the University of California, San Diego.
Twelve patients with HIV who tested within the normal range on neuropsychological tests were compared with 10 normal, HIV-negative controls, 11 HIV-infected patients with mild neurocognitive disorder; and 10 patients with HIV-associated dementia.
Static images produced by high-resolution, two-dimensional MRS imaging of subcortical brain structures targeted differences in commonly tracked markers for N-acetyl-aspartate, choline, and creatine, as well as lactate and lipid markers that indicate levels of resting inflammation and oxidative stress.
Significantly increased levels of lactate and lipid biomarkers were noted in all HIV patients, those who tested normally on neuropsychological tests as well those with mild neurocognitive disorder and HIV-associated dementia, compared with controls. This finding suggests, "even at a resting state, we're starting to see oxidative changes and inflammation in these patients," Dr. Ances said during a podium presentation.
"The hope is that we can start to see these early markers of disease in HIV patients prior to neuropsychological testing deficits," he added in an interview after the meeting.
Functional MRI tests also were conducted, in a group of 39 subjects.
During a simple finger-tapping task, changes were assessed in cerebral blood flow, cerebral metabolic rate of oxygen consumption, and blood oxygen level dependent mapping within a subcortical region, the lenticular nuclei of the basal ganglia. On each measure, significant increases were seen in the 18 neuropsychologically normal HIV-positive subjects, compared with 21 seronegative control subjects.
Among the 18 patients with HIV, pronounced increases in functional neuroimaging measures were seen in 8 acutely infected with HIV, and 10 with chronic HIV infection, suggesting that increased functional metabolic demands caused by HIV occur soon after initial infection, Dr. Ances said.
He noted that there has been a steady increase in the number of patients with neurologic impairment because of HIV, in part "because the patients are living longer with the disease."
The neuroimaging findings suggest that noninvasive imaging techniques might be a valuable addition to neurologic evaluations of patients with HIV, in addition to studies of the virus in cerebrospinal fluid and standard neuropsychological tests.
"These early changes seen with functional MRI suggest that early neuroprotective agents could be considered in these patients," said Dr. Ances, who was awarded a Young Investigator Award for his research from the Conference on Retroviruses and Opportunistic Infections.
BY BETSY BATES
Los Angeles Bureau
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|Title Annotation:||Across Specialties|
|Publication:||Clinical Psychiatry News|
|Date:||Aug 1, 2007|
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