TAT and AIDS dementia complex: The findings that Tat-subtype B, which is the predominant subtype in the USA, but not subtype C (predominant in India), results in significantly higher levels of HIV dementia, 15–30% in the USA compared to 1–2% in India both in pre-therapy era, suggest that neurotoxic potential of Tat protein from different subtypes may vary (Antinori et al., 2007; Heaton et al., 2010, 2011).