Functional MRI can find brain abnormalities in asymptomatic patients

US researchers found that functional magnetic resonance imaging (fMRI) can offer early warning of neurologic morbidity in HIV patients.

“A previous fMRI study demonstrated increased brain activation during working memory tasks in patients with HIV with mild dementia,” wrote Thomas Ernst and colleagues at Brookhaven National Laboratory in Upton, NY, the Massachusetts Institute of Technology- Cambridge and the University of California-Los Angeles Medical Center in Torrance.

Ernst and colleagues discovered that fMRI screening could detect neurologic abnormalities even in patients who have no overt symptoms of dementia. The researchers evaluated the utility of blood oxygenation level-dependent fMRI for finding abnormal brain activity. A group of 10 HIV patients with low CD4 cell counts underwent neuropsychological tests under fMRI. The investigators compared their results with those of age-, sex-, education-, and handedness-matched seronegative controls, according to the study.

Although the HIV patients did not suffer from impaired test performance, fMRI showed significant increases in their lateral prefrontal cortex activation and activated brain volume, data revealed. The asymptomatic patients showed heightened activated brain volume in the lateral prefrontal cortex during all of the assigned tasks, regardless of the difficulty. The investigators found that fMRI measurements of brain activity and activated volume were similar in other regions of the brain between patients and controls.

“Increased brain activation in subjects who are positive for HIV precedes clinical signs or deficits on cognitive tests,” Ernst and colleagues concluded. “ fMRI appears to be more sensitive than clinical and neuropsychological evaluations for detecting early HIV-associated brain injury.”