Dr. Gallant: I was recently told by my doctor that AZT is the only antiviral to "go to the brain," this after I asked about dementia. I now think about this and everyone I have known who developed dementia had been on long-term AZT therapy. Is there a connection? Has anyone checked this out? Or is it just assumed that HIV causes dementia? More than curious, Will

AZT is not the only antiviral to get into the central nervous system. Other drugs that clearly have activity in the brain include d4T, nevirapine, and probably all of the other NNRTIs (non-nucleoside reverse transcriptase inhibitors). In addition, data were presented at the ICAAC meetings in Toronto demonstrating that patients taking ritonavir/saquinavir without any RT inhibitors had undetectable viral loads in their spinal fluid, despite the fact that protease inhibitors aren't supposed to penentrate well into the central nervous system.

HIV causes dementia, not AZT. In fact it is very clear that people on AZT are much less likely to develop dementia, and when high-dose AZT is instituted before the dementia is severe, it can often lead to dramatic improvements. What you've observed simply reflects the fact that despite our treatments, some people with HIV will still go on to develop dementia, and virtually all of them will have taken AZT because just about everyone with HIV has taken AZT at some point or another.