October 4, 2012
In the time before the availability of potent anti-HIV combination therapy (commonly called ART or HAART) one of the feared consequences of HIV infection was dementia. In cases of AIDS-related dementia, people could gradually lose control of their muscles and memory, have difficulty thinking clearly and their personality could undergo drastic changes.
However, the widespread availability of ART today has made AIDS-related dementia relatively uncommon in Canada and other high-income countries. Instead, multiple research studies have found that subtle deficits in thinking and memory persist in ART users. The reasons for these generally mild abnormalities are not clear but may be related to the following or other issues:
Brain cells are very active and require fresh blood rich in oxygen and nutrients, particularly a stable level of glucose, which is used as a source of energy. In HIV-negative people, neurocognitive declineproblems with thinking clearly and rememberinghas in some cases been linked to the following co-morbidities:
Researchers in Italy have conducted a neurocognitive assessment of 245 HIV-positive people and evaluated them for conditions that could affect the important functions of their brain. They found that co-morbidities such as diabetes and other risk factors for poor cardiovascular health did weaken the neurocognitive abilities of participants. It is possible that these metabolic problems could perhaps intensify subtle HIV-related effects on the brain. The research team suggests that by focusing on the diagnosis and treatment of co-morbidities in HIV-positive people, doctors might be able to effect improvements in mild neurocognitive dysfunction.
Researchers in Rome and Galatina, Italy, evaluated 245 HIV-positive participants between July and October 2010. All participants underwent a comprehensive series of neurocognitive tests and also ultrasound scans of the arteries in their neck. These arteries are called the carotid arteries and they supply fresh oxygen-rich blood to the brain. In addition, participants gave blood for tests and were interviewed by the research team.
The average profile of participants upon entering the study was as follows:
The proportion of participants with different cardiovascular risk factors was as follows:
On average, participants had two risk factors for a future heart attack or stroke.
About 31% of participants had narrowed carotid arteries.
A total of 53% of participants had mild neurocognitive impairment detectable only with testing. No participants had any greater degree of this problem and so their ability to carry out daily tasks or work was not affected.
Interestingly, neurocognitive impairment was most common (61%) among participants who had two or more risk factors for cardiovascular disease (CVD).
Taking many factors into account, the researchers found that having narrowed arteries was linked to mild neurocognitive decline. Among people with diabetes, a statistical trend emerged toward poor neurologic functioning.
Among a sub-set of people (206 participants) whose viral loads were less than 50 copies/ml, findings were similar to the larger group.
The research team also assessed the effect of different anti-HIV drugs on neurocognitive abilities and found that participants who used abacavir (Ziagen and in Kivexa and Trizivir) seemed to have better neurocognitive function.
Factors such as lowest-ever CD4+ cell count, current CD4+ count and length of time with HIV infection were not linked to performance on neurocognitive tests.
As an aside, although most of our report focuses on co-morbidities and their effect on neurocognitive function, other researchers have found that, in general, the more educated a person is, the more likely that a decline in neurocognitive function is delayed compared to people who have less education. One study in the U.S. found that a high degree of education might help delay the loss of neurocognitive function in HIV-positive people.
Not surprisingly, in the present study, researchers found that participants who had more than 11 years of schooling performed better on neurocognitive testing.
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