E for Ecstasy by Nicholas Saunders
Appendix 1: Reference Section

72 fax from Rick Doblin, president of MAPS, 21/9/92

Doblin doubts that there is any neurotoxicity due to MDMA at normal doses. When primates were given oral doses of 2.5 mg/kg once every 2 weeks for 4 months (total of 8 doses) there was no evidence of neurotoxicity. But a single dose of 5 mg/kg did cause some slight reduction in the serotonin levels in two parts of the brain, the thalamus and the hypothalamus. So, it is possible that MDMA may be causing some toxicity in people who use especially high doses. Still, whether that toxicity is bad is not at all certain. In primates with 90% reductions in serotonin caused by massive amounts of MDMA (5 mg/kg injected every 12 hours for 4 days) there are no observable long term negative consequences. Still, damage may be too subtle to observe in primates.