Researchers Demonstrate Effect of HIV on the Brain with fMRI

Researchers Demonstrate Effect of HIV on the Brain with fMRI

Researchers at Stellenbosch University (SU) in South Africa have studied the effect of HIV on the brain and have shown that in the early stages of infection, HIV does impact the brain and can cause cognitive symptoms.

Many patients have negative cognitive symptoms following infection with the HIV virus. Oftentimes, these symptoms have been attributed to the patients feeling sick, tired, or depressed.

Some studies have suggested that as many as 50% of HIV patients have some form of cognitive impairment, ranging from mild symptoms to severe psychosis and HIV-related dementia. However, the relationship between HIV and these common symptoms is not well understood.

Dr Stéfan du Plessis and his team at SU studied the effect of HIV on the brain using functional magnetic resonance imaging (fMRI). fMRI scans show blood flow in the brain, and if performed while patients perform certain cognitive tasks, researchers can determine how blood flow and brain activity differs in patients diagnosed as having contracted HIV.

The SU researchers analyzed blood flow to certain parts of the brain in HIV patients and a control group of healthy volunteers. The HIV patients were in good health, were not currently receiving antiretroviral treatments, and were not abusing drugs.

Compared to the control group, the HIV patients were observed to have reduced blood flow in the striatal region of the brain during tasks involving high motor functions and little activity and blood flow in the nucleus accumbens when performing a task involving a monetary reward.  The nucleus accumbens, a region in the basal forebrain rostral to the preoptic area of the hypothalamus, is known to be involved with motivation, and feelings of apathy and enthusiasm.

“The fMRI scans show how the HIV virus affects important parts of the brain involved with motivation. We theorise that this could happen to such an extent that patients are often simply not motivated enough to take their medication, or even get out of bed,” said Dr Stéfan du Plessis.

The researchers also identified a link between HIV-related atrophy in the frontal cortex and functional impairment, with a correlation between the thickness of the actual frontal lobe and the level of functional impairment. The thinner the actual frontal lobe, the lower the level of function.

Dr. Du Plessis said, “The study highlights a previously unknown functional effect that HIV has on the brain. We hope that these results will stimulate further studies to test the effects of ARVs, or other interventions, that could improve brain function and therefore the lives and well-being of patients with HIV.”

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