A very nasty virus

HIV's punch brings on dementia | The Australian

It is a commonly held belief that rates of HIV infection are increasing in some communities because anti-viral therapy has made it seem that it is not a complete disaster to catch the disease, thereby inadvertently encouraging some risk taking behaviour.

I have suggested before that education about the disease ought to address this issue: show a few HIV positive people who are alive, but far from well, despite being on the best therapy available. (Who knows, maybe this line is already being followed in some advertising campaigns directed at the gay community?)

Anyway, this story today serves as a reminder of the seriousness of the infection:

THE reason many people with HIV-AIDS develop dementia has long baffled researchers, but scientists finally believe they have the answer - the virus hits the brain with a one-two punch.

First, a protein on the surface of the virus directly kills brain cells, or neurons. Then the same protein disrupts the formation of new neurons from adult stem cells.

In people, the dementia triggered by the virus, HIV-associated dementia (HAD), slows thinking, memory and even movement.

Perversely, although highly active anti-retroviral therapy (HAART) helps HIV-infected people live longer and with less severe dementia, the prevalence of HAD has not declined.

Statistics from the National Centre in HIV Epidemiology and Clinical Research (NCHECR) at the University of NSW in Sydney reveal that almost 9800 Australians have HIV-AIDS.

According to Bruce Brew -- head of neurology at St Vincent's Hospital in Sydney -- roughly 20 per cent of people with AIDS will develop HAD. Surprisingly, many will remain otherwise quite well.

In the BCC report on the same research, it is noted:

Keith Alcorn, senior editor of the HIV information service NAM, said: "The discovery that HIV affects stem cell proliferation in the brain is bound to add to concerns that people with HIV doing well on antiretroviral therapy may nevertheless face a higher risk of dementia in years to come.

"Antiretroviral drugs have lowered viral load so that HIV will not kill cells directly, but we don't know the consequences for brain functioning of a long-term low level of infection.

"It may be that low level infection is enough to interfere with the regeneration pathways in the way shown in this experiment."