PURPOSE: Animal data suggest that the synthetic drug ecstasy may damage brain serotonin neurons. Previously we reported protracted reductions in the availability of the serotonin transporter (SERT), an index of integrity of the axon terminals of brain serotonergic neurons, in SERT-rich brain regions in current human ecstasy users. Comparison of current ecstasy users and former ecstasy users yielded some evidence that this reduction might be reversible. However, participant selection effects could not be ruled out. Therefore, follow-up examinations were performed in these subjects to test the following a priori hypothesis in a prospective longitudinal design that eliminates participant selection effects to a large extent: availability of the SERT increases towards normal levels when ecstasy use is stopped, and remains unchanged or is further decreased if use is continued. METHODS: Two follow-up positron emission tomography measurements using the SERT ligand [11C](+)McN5652 were completed by 15 current and nine former ecstasy users. All subjects used illicit drugs other than ecstasy, too. The time interval between repeated measurements was about 1 year. The time course of the availability of the SERT was analysed in the following SERT-rich regions: mesencephalon, putamen, caudate and thalamus. RESULTS: Current ecstasy users showed a consistent increase in the availability of the SERT in the mesencephalon during the study (Friedman test: p = 0.010), which most likely was caused by a decrease in the intensity of ecstasy consumption (Spearman correlation coefficient -0.725, p = 0.002). Former ecstasy users showed a consistent increase in SERT availability in the thalamus (Friedman test: p = 0.006). CONCLUSION: Ecstasy-induced protracted alterations in the availability of the SERT might be reversible.
