Why do a quarter of people with HIV develop dementia

Main Category: HIV / AIDS
Article Date: 20 Apr 2004 - 0:00 PDT

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Scientists say they have discovered why some people with HIV develop dementia. They say proteins are produced by the virus, these proteins kill brain cells.

The scientists work at Thomas Jefferson University, Philadelphia, USA.

You can read about this in the journal Proceedings of the National Academy of Sciences.

Many charities and AIDS organisations have said that this research and its findings could help many patients.

Scientists have been baffled for decades. HIV does not cause brain inflammation or white blood cell increase, usually associated with infections such as meningitis or herpes.

What HIV does is that it causes the nerve cells (neurons) to die.

Dr Roger Pomerantz, Jefferson Medical College, said that this was not a common way infectious agents work at all, in fact, it is extremely unusual.

Scientists used to think the HIV infected macrophages and miroglia, these then produced cytokines and chemokines, and these killed the neurons.

The researchers wanted to know whether the virus itself killed the nerve cells or whether infected cells produced something that killed the nerve cells.

They examined brain cells and T-lymphocyte blood cells. They took the virus out of some and left it in others.

When applied to the nerve cells, they found they were killed when the virus and its proteins were present.

Dr Pomerantz said of this "When we looked at T-cells, the only thing that killed neurons was the virus. Once the virus is removed, nothing from the T-cells would kill neurons."

After some microarray technology, they saw that cytokines and chomkines levels were low. So, obviously they were not causing the dementia.

After investigating the neurons themselves, they found two well-defined pathways to cell death, which were activated by proteins from the virus.

Dr Pomerantz said "We feel that it is mainly the virus and viral proteins causing the neuronal cell death, and may now know the precise pathways involved."

By knowing the precise pathways involved it may be possible to develop treatments which prevent the virus damaging the neurons, he said.

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