Originally appearing at http://www.guardian.co.uk/theobserver/2011/mar/27/letters-vocational-training-schools. You recently reported: “There is no evidence that ecstasy causes ‘brain damage’“, in an article based on a new study by Halpern and colleagues. We were rather surprised, since in hundreds of our research publications we have presented reliable scientific evidence for cognitive and other deficits in ecstasy users. Furthermore, the Halpern study in Addiction does indicate significant cognitive impairments. Their ecstasy-user group was a highly selected sample, yet despite this careful pattern of drug usage, the users displayed several neurocognitive deficits. They occurred in psychological functions known to be sensitive to MDMA, such as memory and higher cognition, while depression was also higher in the heavier users. Turning to the wider question of “brain damage”, MDMA primarily affects the neurotransmitter serotonin. Several large studies have indicted “serotonergic neurotoxicity” in ecstasy users. The most recent showed significant reductions of Sert (the serotonin transporter) in every region of the cerebral cortex. The extent of these Sert reductions was associated with lifetime ecstasy use and the degree of neurocognitive deficit. Halpern and colleagues have shown that mild cognitive deficits can occur even in light and relatively careful ecstasy users. Professor Andrew C Parrott Swansea University Dr. Norberto Aguirre, University of Navarra, Pamplona, Spain. Dr. Jillian Broadbear, Monash University, Australia. Dr. John Brown, Australian National University, Canberra. Dr. Raimondo Bruno, University of Tasmania, Australia Dr Tom Buchanan, University of Westminster, London, UK. Professor Félix Carvalho, University of Porto, Portugal. Dr. Joerg Daumann, University Hospital of Cologne, Germany. Professor John Fisk, University of Central Lancashire, UK. Professor Francesco Fornai, University of Pisa, Italy. Dr. Helen Fox, Yale University, USA. Professor Gilberto Gerra, United Nations Office on Drugs, Vienna, Austria. Florentia Hadjiefthyvoulou, University of Central Lancashire, UK Dr. Tom Heffernan, Northumbria University, UK Professor Rod Irvine, University of Adelaide, Australia. Dr. Katy Jones, Turning Point Drug Centre, Melbourne, Australia. Dr Tatia Lee, University of Hong Kong. Dr. Jon Ling, University of Sunderland, UK. Dr Allison Matthews, University of Tasmania, Australia. Professor Una McCann, Johns Hopkins University, USA. Dr. Raffaella Milani, Thames Valley University, UK. Dr. Michael Morgan, Sussex University. Dr. Philip Murphy, Edge Hill University, UK Professor Boris Quednow, University of Zürich, Switzerland. Dr. Liesbeth Reneman, Academic Medical Center, Amsterdam. Professor George Ricaurte, Johns Hopkins University, USA. Dr. Jacqui Rodgers, Newcastle University, UK. Dr. Abdallah Salem, University of Adelaide, Australia. Dr Susan Schenk, Wellington University, New Zealand. Professor Andrew Scholey, Swinburne University, Australia. Jennifer Seddon, University of Birmingham, UK Professor Lynn Singer, Case Western Reserve University, USA. Professor Con Stough, Swinburne University, Australia. Professor Rainer Thomasius, University Medical Centre, Hamburg, Germany Dr. John Turner, University of East London, UK. Dr. Robbert Verkes, Radboud University Nijmegen Medical Centre, Netherlands. Dr. Joris Verster, Utrecht University, Netherlands. Dr. Mark A Wetherell, University of Northumbria, UK. Dr. Kim Wolff, King’s College London, UK. Professor Bryan Yamamoto, University of Toledo, Ohio, USA. What follows is a letter to the editor published on Sunday, March 27, 2011, in the Guardian, signed by abut 40 scientists all objecting to the findings of Dr. John Halpern’s paper in the journal Addiction, which found no association between long-term recreational Ecstasy use and cognitive damage. On April 3, Prof. Stephen Kish responded to the letter with one of his own.