Another legend, often mentioned together with the "holes in the brain" myth discussed above, is that MDMA causes Parkinson's disease, possibly with even one night of exposure. This was partially based on an animal study that found neurotoxicity to dopaminergic neurons after administering the drug to monkeys. However, the study has been retracted by the researchers who conducted it because they had accidentally given methamphetamine instead of MDMA to the animals, given the similar chemical names (MDMA stands for 3,4-methylenedioxymethamphetamine). Ironically, it is now being investigated as a possible "treatment" for Parkinson's disease.