As the glycoprotein gp120 from the envelope of HIV-1 binds directly to CXCR4 and has direct neurotoxic effects, CXCR4 is likely to be crucial for different aspects of CNS HIV infection and the development of AIDS dementia, and CXCL12 could have neuroprotective effects in this context as well as in other forms of damage. This evidence concerns the gene CXCR4 and AIDS dementia complex.