THE ARTICLE by Reneman et al1 in this issue of the ARCHIVES is timely and provocative and highlights several areas of controversy in the fields of substance abuse, drug-induced neurotoxic effects, and neuroimaging. The authors present evidence that the illicit recreational drug 3,4-methylenedioxymethamphetamine (MDMA, or "ecstasy") may cause persistent cognitive deficits2-9 and that these deficits are related to the extent of previous MDMA use. Based on single-photon emission computed tomography (SPECT) imaging with 123I-labeled 2β-carbomethoxy-3β-(4-iodophenyl)tropane (β-CIT), they conclude that MDMA causes neurotoxic injury to cortical serotonin (5-HT) axon terminals that may be reversible. This is the first study to evaluate a separate cohort of previous MDMA users who have abstained from use for longer than 1 year, and thus has the potential to provide information regarding long-term effects of exposure to MDMA.