Neurotoxicity is probably also related to people overheating and overexerting themselves while on the drug - I've seen people sweating profusely and not noticing while rolling a few too many times.. which generally results in me giving them water, salty crackers, and nudging them to consider taking a quick break.
Indeed - the more visible research papers about amphetamine-related neurotoxicity in rodents reported most effects when the temperature in the brain exceeded 40 degrees - contributing towards massive oxidative stress.
Is oxidative-stress the only mechanism of neurotoxic action, or are there other effects at work, such as dopamine-downregulation or exhaustion?