n In studies of people who used methamphetamine over the long term, severe changes also affected areas of the brain involved with emotion and memory.2 This may explain many of the emotional and cognitive problems seen in those who use methamphetamine. Studies indicate that HIV causes more injury to nerve cells and more cognitive problems in people who use methamphetamine than it does in people who have HIV and don't use the drug.1 Cognitive problems are those involved with thinking, understandi...